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I am working on designing a user interface and want to convey my design to my peers. Typically, I'd use a mock-up of the UI and UML, but given the complexity, size, and multiple asynchronous interactions I'm not sure that this makes the most sense. It doesn't seem to allow to efficiently describe the process.
Does anyone have experience in designing large User Interface's? How would a company that designs UI's go about modeling their process/ design? This seems to be a question for the 'front-end' engineers.
well let's go for an answer even if your question is very large. I'll give you my experience and hope it will help you to decide.
To my mind, using UML in a project is very useful if you use it right, it's often clear, quite easy to understand. On the other side, when working on huge project, it's sometimes costly because it takes time to create your diagrams and nowadays, you have to be as fast as possible !
These last months I have worked on a project with a GUI and to well define it, I have first draw some screen on paper and quickly ask for some drawbacks near the coffee machine.
I have created some activity diagrams and then, created a mock-up.
How to choose now ?
First of all, if your GUI should have a beautiful design, I don't think you can avoid a mock-up, but I'm don't know if it's your goal.
My main tip would be, try to simplify your complexity in your program. If you have multiple asynchronous that could arise everytime/everywhere, you'll encounter a lot a problem.
In my project, let's say my tablet could be preempted by an external computer whenever/wherever. I just have created a class beforehand to manage this asynchronous call but my sub-activity-diagrams stayed intact.
Draw specific diagram for specific functionalities and leave useless diagrams which are not relevant/too simple.
Hard to explain you more than this without giving you any example. Hope it will help a bit.
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Does anyone actually think this is a good reason to "Dumb down" your code?
When a manager asks you to make your code simple (in terms of technology skills required to understand it) at the cost of more verbose cluttered code what should you do?
I highly disagree. Junior developers will end up being Senior developers. How? By encountering advanced topics that aren't taught in school.
My code base now makes heavy use of Inversion of Control containers. I would never revert my code to the old way because a junior developer had issues groking IoC. Instead I would take them out for a beer after work and discuss it. The more the junior dev learns the less hand holding needs to be done.
Here's a blog post discussing this very topic.
If you're constantly dumbing down your code or designs, it's a pretty good way to make sure your junior developers stay dumb. Challenge them and use it as a mentoring opportunity. Of course, some will never learn, but you've got bigger problems at that point.
It's not just pointy-haired bosses either. As a senior dev, it's often difficult to resist the urge to mommy junior developers. "Oh I'll just do this part because it's way too hard for them", or it'll take them too long, or they'll get way off in the weeds.
And finally, make sure you strike a balance between idiomatic code that uses the full power of a language vs idiomatic code that abuses that power. There's no reason you need to override the || operator just to run its args in two separate threads. At least dumb the code down a little for your older, dumber, future self.
Well, I think it's reasonable to avoid using "clever" language constructs unless they really, really make the code better - at which point if a junior developer sees it, hopefully they'd ask rather than just being flumoxed.
Here's an alternative way of phrasing it though: "Write your code so that it's easy enough to understand that if you get called at 3am and asked to fix a bug in it, you can still understand it."
Seriously, make it as easy to understand as possible. That doesn't mean a comment every other line - it means a comment where the purpose of a piece of code isn't obvious, and only then where the preferred choice of "well make it obvious then" doesn't work.
There's a difference between puzzle code and complex code.
I've found that the single biggest issue is that there is a big difference between "easy to understand by reading" versus "well-factored", and that the two goals are often in direct tension with one another. In well-factored code, there is a lot more jumping around between classes and a lot of virtual dispatch, so the path through the code is very non-linear.
Yes readability and being able to easily understand code is a big part of maintainability in my opinion.
Well if you intend to maintain your code forever, never change jobs, never feel the urge to work on something new, and can assure everyone you will never be hit by a truck, then sure there is no need to dumb down that puzzle code.
No. In the past, I've learned a lot from seeing the tricks of more experienced developers. I'd much rather have had the opportunity to learn something new from them than have had them dumb things down for me.
Its a balancing act...
If any 3 people on your team can 'read' your code and know what its doing... no need to change. However if you're the only person who can understand your code (no matter how rad/clever you think it is).. maybe you should take it down a few notches.
Another guideline to help would be to 'Try the simplest thing that works.' All the latest buzz words are nice to know however what it is even more important is having the skill to spot where you could get by without using them. You don't need to spray paint your code with IOC or Frameworks or Design Patterns...
The manager's side of this argument is sorely missed in this thread :) (and for the record.. I'm not one). His/Her major concern being he doesn't want a dark area of code that no one else dares to venture into.. so if you can convince your boss that a few other people on the team can make an arbitrary fix (or better yet.. show an actual bug fixed by someone else) - the mgr should let you off the hook. Disagreeing with your boss is another art :).. but you can talk things out usually.
You dont have to go all the way backward to Lowest Common Denominator.. strike a balance.
Your goal should not be for your code to be easy to understand for a junior developer. Instead, it should be easy to understand for a maintainence programmer.
This means:
Local "complexity" is okay, when needed. If they see the complex code they'll know they need to dig deeper.
Hidden complexity is bad. If you can't see that changing a piece of code will have subtle side effects then maintaining the code will be a nightmare.
New technologies that are visible are also okay, when not taken to extremes.
This is because those that maintain code rarely have the same overall understanding of the system. Or the time to develop it.
I disagree with the manager: What needs to be simple is the code, not the technology used to write it.
I would, however, impose a closely related requirement:
The internal documentation states clearly what technologies are needed to understand this code, and it gives references to places where those technologies can be learned.
For example, even as a senior developer, I find all matrix codes baffling. But if somebody gives me a reference to the right part of Numerical Recipes, I can puzzle out the details.
Yes. It's a very valid reason to take it down a notch. The reality is that a very, very large number of developers (as in most) are at the junior level.
As far as what you should do... Say "Yes Sir" or "Yes Ma'am" and do it. There is only one boss in that relationship.
UPDATE:
As some people seem to think that having a jr dev learning advanced topics while wading through obfuscated code I want to throw one more thing in here.
When ANY developer (jr or otherwise) runs into code they don’t understand, their first approach is to refactor it into something that is understandable. This is called the “Wow that code is crap I must rewrite it!” syndrome. I’m willing to bet everyone on this board has experienced it. So, as a business owner, do I want to pay for code to be developed each time a new person comes by or do I want to pay for new features to be added?
Guess which person I’m going to keep around longer.
If you dumb down your code, you're going to be stuck working with dummy junior programmers who will never be familiar with advanced coding techniques. If there's any verbose code that's trying to express an inherently complex procedure that you wrote, the aforementioned junior developer probably wouldn't be able to see the forest for the trees anyways. And they'd probably screw up if they had to express a complex concept if all they knew were basic primitive constructs whereas if they knew how to express what they meant tersely and elegantly, the code has a better chance of being correct.
Scott Muc said:
"I've found that the single biggest issue is that there is a big difference between "easy to understand by reading" versus "well-factored", and that the two goals are often in direct tension with one another. In well-factored code, there is a lot more jumping around between classes and a lot of virtual dispatch, so the path through the code is very non-linear."
Quoted for truth, and I think this is one of the biggest problems with C++ code in general. If you're the one that wrote the code, it's pretty easy to come up with a very complicated set of stuff that is well factored, makes lots of sense if you already know it, works well, and generally resembles a diamond crystal, etc. but which, from the perspective of someone who's trying to figure out how you got there and why things are the way they are and how things work, and how one might make changes that fit into the existing system and satisfy new requirements, is almost completely opaque and impenetrable.
How does this kind of situation help maintainability? That situation is one of my main beefs with C++ programmers. Far better to have a mess of plain C code which can be hacked upon than a diamond crystal of inpenetrably super-factored code which nearly nobody can figure out how to sensibly modify without smashing the crystalline structure.
One way to "dumb down" code that I actually think is an excellent practice is to use longer variable names and longer function names. Naming variables and functions to make their purpose easily understandable is a significant engineering task, IMHO, and takes extra effort on the part of the original author of the code. Damian Conway has some excellent examples in "Perl Best Practices". Some examples include: Prefer "final_total" to "sum"; prefer "previous_appointment" to "previous_elem", prefer "next_client" to "next_elem". Prefer "sales_records" to "data". Etc. He also pushes for using grammatical templates (Noun-adjective) and staying consistent. Don't use max_displacement one place and then use VelocityMax in another. Index variables need real names too:
sales_record[i] vs sales_record[cancelled_transaction_number]
I frequently "refactor" my code at the end of a development cycle by finding new names for all my functions and variables. In a modern editor it's trivial to change them all, and it's only at the end that I really figure out what I used them for. "Dumbing down" code this way isn't classic C, but it's easier for me when I come back months later asking WTF did I do?
It depends on the code. Is this something being shipped in your flagship product that requires use of the features your manager wants you to remove for performance reasons? If the answer is yes I would try to have your manager let you keep the code and just write up a document explaining in detail the section of code that is hard to understand. If it's an internal app that needs to be maintained by lots of different people and the complex features can be removed with out negatively affecting the program remove them and pick more important battles to fight.
You should just remind your boss that you can build rocket ships or chicken coops, and he will have to pay you the same for either one. Do what they say but generally an environment like that lends itself to people looking for a new environment.
The old quote is appropriate here:
Make everything as simple as possible,
but not simpler.
I've known developers who wrote highly obfuscated code that they felt was advanced but which the rest of the team felt was unreadable and unmaintainable. Part of this involved overuse of advanced language features (in C, the ternary operator and the comma operator) and writing in an obscure personal idiom (for example, replacing ptr->item with (*ptr).item everywhere) that no-one else would ever be able to maintain. The author was trying to outsmart the optimizer (which to be fair, was far from good).
Note: I'm not suggesting that "x = (p == NULL) ? "default" : p->value;" is complicated, but when someone uses ternary operators that span many lines, are nested, and make heavy use of the comma operator, code quickly becomes unreadable.
In this sort of case, "dumbing down" the code would have been a good idea. The problem was not advanced algorithms nor advanced language features, but overuse and inappropriate use of advanced language features, and an obscure personal idiom.
However, in the case you are asking about, where the manager's changes make the code more difficult to read and maintain, I agree with you and the others who have responded. I just wanted to point out the alternative that no-one else has mentioned.
I suggest keeping the code in a "Geeky-level" and comment it well so that the juniors can understand the intention behind the code and simultaneously learn a better way (or a right way) to code, so we have the best of both he worlds.
I think it is the manager's way of politely telling you that your code is too obfuscated/complex/jumbled/puzzle code...whatever you want to call it. Sometimes we get so involved writing our codes that we forget that someone else will have to come along and read it later.
I learned it the hard way and, in retrospect, find that it was the better way. Let the cycle repeat itself.
I agree 100% with the argument. With one major addition: Train your junior developers until they understand your code ;-)
I'm talking about using "unusual" technologies. In this case it's JQuery.
This issue came up when I was writing a wizard control for user registration.
The navigation menu needed to be customised and the current step in the wizard had to have a different css class in the menu. This meant I needed to get access to the currently selected step when generating the menu. My solution was to output the current step index in a hidden html field which could then be read by JQuery in order to customise the css.
I thought that this was much nicer and cleaner than using the databinding syntax in ASP.NET which doesn't have compile-time checking and messes up the layout of the html.
The databinding solutions is "standard" while the JQuery one is "unusual" which means that it's less likely to be understood by a junior.
I'm trying more and more these days to provide the required data for the UI rather than hack it into the UI with databinding which is why I added the hidden field with the current step index.
It is simply impossible to make progress or to innovate in any industry without doing things that others don't understand. Innovation is necessarily blasphemous. Why? Because if you're doing things that make sense to everyone else around you, the odds are you're not the first one doing it. ;)
That being said, there is a significant difference between doing something that is difficult to understand simply because it's a new or complicated problem versus doing something that's difficult to understand because you're trying to show off or you think confusing people will somehow gain you job security (which I've never seen work, but I've heard of people trying).
Should you make things easy to understand? Yes absolutely, as much as humanly possible. However a program that works and does its job well is the higher priority.
The manager's complaint should never be "don't do this because our junior guys don't understand it" -- it should only ever be "do x instead of y whenever feasible because x is easier to read / understand". This also assumes that x and y are equivalent (accept the same input and produce the same result).
I can't stand when managers do that... I've had three different managers bawl me out for using perfectly normal code the way it was designed to work, not because I was doing anything complicated, but rather only because they felt like it was too much effort for the other guys on our team to go RTFM on the language we were using. As a management strategy, that's totally backwards. It's like being the Holy Roman Catholic church and insisting that the laymen are too dumb to be trusted with literacy.
If you want to know really how ridiculous some of these managers get, try this: I had one manager bawl me out for declaring a variable as a type of "boolean" because he didn't feel the other programmers could handle it. Actually when I asked why, his answer was "because we don't do that here", which is a non-answer, but I interpreted it to mean "dumb it down". They were also berating me for that and similar practices as though it should be obvious that good programming habits were actually "bad" and that I should already know why even though they had never expressed a preferred programming style (either formally or informally). Needless to say, it was a bad job.
Make sure you can understand what it does 6 months down the road.
When in doubt, COMMENT your code. That's what comments are for.
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I've inherited a project where the class diagrams closely resemble a spider web on a plate of spaghetti. I've written about 300 unit tests in the past two months to give myself a safety net covering the main executable.
I have my library of agile development books within reach at any given moment:
Working Effectively with Legacy Code
Refactoring
Code Complete
Agile Principles Patterns and Practices in C#
etc.
The problem is everything I touch seems to break something else.
The UI classes have business logic and database code mixed in. There are mutual dependencies between a number of classes. There's a couple of god classes that break every time I change any of the other classes. There's also a mutant singleton/utility class with about half instance methods and half static methods (though ironically the static methods rely on the instance and the instance methods don't).
My predecessors even thought it would be clever to use all the datasets backwards. Every database update is sent directly to the db server as parameters in a stored procedure, then the datasets are manually refreshed so the UI will display the most recent changes.
I'm sometimes tempted to think they used some form of weak obfuscation for either job security or as a last farewell before handing the code over.
Is there any good resources for detangling this mess? The books I have are helpful but only seem to cover half the scenarios I'm running into.
It sounds like you're tackling it in the right way.
Test
Refactor
Test again
Unfortunately, this can be a slow and tedious process. There's really no substitute for digging in and understanding what the code is trying to accomplish.
One book that I can recommend (if you don't already have it filed under "etc.") is Refactoring to Patterns. It's geared towards people who are in your exact situation.
I'm working in a similar situation.
If it is not a small utility but a big enterprise project then it is:
a) too late to fix it
b) beyond the capabilities of a single person to attempt a)
c) can only be fixed by a complete rewriting of the stuff which is out of the question
Refactoring can in many cases be only attempted in your private time at your personal risk. If you don't get an explicit mandate to do it as part of you daily job then you're likely not even get any credit for it. May even be criticized for "pointlessly wasting time on something that has perfectly worked for a long time already".
Just continue hacking it the way it has been hacked before, receive your paycheck and so on. When you get completely frustrated or the system reaches the point of being non-hackable any further, find another job.
EDIT: Whenever I attempt to address the question of the true architecture and doing the things the right way I usually get LOL in my face directly from responsible managers who are saying something like "I don't give a damn about good architecture" (attempted translation from German). I have personally brought one very bad component to the point of non-hackability while of course having given advanced warnings months in advance. They then had to cancel some promised features to customers because it was not doable any longer. Noone touches it anymore...
I've worked this job before. I spent just over two years on a legacy beast that is very similar. It took two of us over a year just to stabilize everything (it's still broke, but it's better).
First thing -- get exception logging into the app if it doesn't exist already. We used FogBugz, and it took us about a month to get reporting integrated into our app; it wasn't perfect right away, but it was reporting errors automatically. It's usually pretty safe to implement try-catch blocks in all your events, and that will cover most of your errors.
From there fix the bugs that come in first. Then fight the small battles, especially those based on the bugs. If you fix a bug that unexpectedly affects something else, refactor that block so that it is decoupled from the rest of the code.
It will take some extreme measures to rewrite a big, critical-to-company-success application no matter how bad it is. Even you get permission to do so, you'll be spending too much time supporting the legacy application to make any progress on the rewrite anyway. If you do many small refactorings, eventually either the big ones won't be that big or you'll have really good foundation classes for your rewrite.
One thing to take away from this is that it is a great experience. It will be frustrating, but you will learn a lot.
I have (once) come across code that was so insanely tangled that I couldn't fix it with a functional duplicate in a reasonable amount of time. That was sort of a special case though, as it was a parser and I had no idea how many clients might be "using" some of the bugs it had. Rendering hundreds of "working" source files erroneous was not a good option.
Most of the time it is imminently doable, just daunting. Read through that refactoring book.
I generally start fixing bad code by moving things around a bit (without actually changing implementation code more than required) so that modules and classes are at least somewhat coherent.
When that is done, you can take your more coherent class and rewrite its guts to perform the exact same way, but this time with sensible code. This is the tricky part with management, as they generally don't like to hear that you are going to take weeks to code and debug something that will behave exactly the same (if all goes well).
During this process I guarantee you will discover tons of bugs, and outright design stupidities. It's OK to fix trivial bugs while recoding, but otherwise leave such things for later.
Once this is done with a couple of classes, you will start to see where things can be modularized better, designed better, etc. Plus it will be easier to make such changes without impacting unrelated things because the code is now more modular, and you probably know it thoroughly.
Mostly, that sounds pretty bad. But I don't understand this part:
My predecessors even thought it would
be clever to use all the datasets
backwards. Every database update is
sent directly to the db server as
parameters in a stored procedure, then
the datasets are manually refreshed so
the UI will display the most recent
changes.
That sounds pretty close to a way I frequently write things. What's wrong with this? What's the correct way?
If your refactorings are breaking code, particularly code that seems to be unrelated, then you're trying to do too much at a time.
I recommend a first-pass refactoring where all you do is ExtractMethod: the goal is simply to name each step in the code, without any attempts at consolidation whatsoever.
After that, think about breaking dependencies, replacing singletons, consolidation.
If your refactorings are breaking things, then it means you don't have adequate unit test coverage - as the unit tests should have broken first. I recommend you get better unit test coverage second, after getting exception logging into place.
I then recommend you do small refactorings first - Extract Method to break large methods into understandable pieces; Introduce Variable to remove some duplication within a method; maybe Introduce Parameter if you find duplication between the variables used by your callers and the callee.
And run the unit test suite after each refactoring or set of refactorings. I'd say run them all until you gain confidence about which tests will need to be rerun every time.
No book will be able to cover all possible scenarios. It also depends on what you'll be expected to do with the project and whether there is any kind of external specification.
If you'll only have to do occasional small changes, just do those and don't bother starting to refactor.
If there is a specification (or you can get someone to write it), consider a complete rewrite if it can be justified by the foreseeable amount of changes to the project
If "the implementation is the specification" and there are a lot of changes planned, then you're pretty much hosed. Write LOTS of unit tests and start refactoring in small steps.
Actually, unit tests are going to be invaluable no matter what you do (if you can write them to an interface that's not going to change much with refactorings or a rewrite, that is).
See blog post Anatomy of an Anti-Corruption Layer, Part 1 and Anatomy of an Anti-Corruption Layer, Part 2.
It cites Eric Evans, Domain-Driven Design: Tackling Complexity in the Heart of Software:
Access the crap behind a facade
You could extract and then refactor some part of it, to break the dependencies and isolate layers into different modules, libraries, assemblies, directories. Then you re-inject the cleaned parts in to the application with a strangler application strategy. Lather, rinse, repeat.
Good luck, that is the tough part of being a developer.
I think your approach is good, but you need to focus on delivering business value (number of unit tests is not a measure of business value, but it may give you an indication if you are on or off track). It's important to have identified the behaviors that need to be changed, prioritize, and focus on the top ones.
The other piece of advise is to remain humble. Realize that if you wrote something so large under real deadlines and someone else saw your code, they would probably have problems understanding it as well. There is a skill in writing clean code, and there is a more important skill in dealing with other people's code.
The last piece of advise is to try to leverage the rest of your team. Past members may know information about the system you can learn. Also, they may be able to help test behaviors. I know the ideal is to have automated tests, but if someone can help by verifying things for you manually consider getting their help.
I particularly like the diagram in Code Complete, in which you start with just legacy code, a rectangle of fuzzy grey texture. Then when you replace some of it, you have fuzzy grey at the bottom, solid white at the top, and a jagged line representing the interface between the two.
That is, everything is either 'nasty old stuff' or 'nice new stuff'. One side of the line or the other.
The line is jagged, because you're migrating different parts of the system at different rates.
As you work, the jagged line gradually descends, until you have more white than grey, and eventually just grey.
Of course, that doesn't make the specifics any easier for you. But it does give you a model you can use to monitor your progress. At any one time you should have a clear understanding of where the line is: which bits are new, which are old, and how the two sides communicate.
You might find the following post useful:
http://refactoringin.net/?p=36
As it is said in the post, don't discard a complete overwrite that easily. Also, if at all possible, try to replace whole layers or tiers with third-party solution like for example ORM for persistence or with new code. But most important of all, try to understand the logic (problem domain) behind the code.
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I was asked to do a code review and report on the feasibility of adding a new feature to one of our new products, one that I haven't personally worked on until now. I know it's easy to nitpick someone else's code, but I'd say it's in bad shape (while trying to be as objective as possible). Some highlights from my code review:
Abuse of threads: QueueUserWorkItem and threads in general are used a lot, and Thread-pool delegates have uninformative names such as PoolStart and PoolStart2. There is also a lack of proper synchronization between threads, in particular accessing UI objects on threads other than the UI thread.
Magic numbers and magic strings: Some Const's and Enum's are defined in the code, but much of the code relies on literal values.
Global variables: Many variables are declared global and may or may not be initialized depending on what code paths get followed and what order things occur in. This gets very confusing when the code is also jumping around between threads.
Compiler warnings: The main solution file contains 500+ warnings, and the total number is unknown to me. I got a warning from Visual Studio that it couldn't display any more warnings.
Half-finished classes: The code was worked on and added to here and there, and I think this led to people forgetting what they had done before, so there are a few seemingly half-finished classes and empty stubs.
Not Invented Here: The product duplicates functionality that already exists in common libraries used by other products, such as data access helpers, error logging helpers, and user interface helpers.
Separation of concerns: I think someone was holding the book upside down when they read about the typical "UI -> business layer -> data access layer" 3-tier architecture. In this codebase, the UI layer directly accesses the database, because the business layer is partially implemented but mostly ignored due to not being fleshed out fully enough, and the data access layer controls the UI layer. Most of the low-level database and network methods operate on a global reference to the main form, and directly show, hide, and modify the form. Where the rather thin business layer is actually used, it also tends to control the UI directly. Most of this lower-level code also uses MessageBox.Show to display error messages when an exception occurs, and most swallow the original exception. This of course makes it a bit more complicated to start writing units tests to verify the functionality of the program before attempting to refactor it.
I'm just scratching the surface here, but my question is simple enough: Would it make more sense to take the time to refactor the existing codebase, focusing on one issue at a time, or would you consider rewriting the entire thing from scratch?
EDIT: To clarify a bit, we do have the original requirements for the project, which is why starting over could be an option. Another way to phrase my question is: Can code ever reach a point where the cost of maintaining it would become greater than the cost of dumping it and starting over?
Without any offense intended, the decision to rewrite a codebase from scratch is a common, and serious management mistake newbie software developers make.
There are many disadvantages to be wary of.
Rewrites stop new features from being developed cold for months/years. Few, if any companies can afford to stand-still for this long.
Most development schedules are difficult to nail. This rewrite will be no exception. Amplify the previous point by, now, a delay in development.
Bugs that were fixed in the existing codebase through painful experience will be re-introduced. Joel Spolsky has more examples in this article.
Danger of falling victim to the Second-system effect -- in summary, ``People who have designed something only once before try to do all the things they "didn't get to do last time", loading the project up with all the things they put off while making version one, even if most of them should be put off in version two as well.''
Once this expensive, burdensome rewrite is completed, the very next team to inherit the new codebase is likely to use the same excuses for doing another rewrite. Programmers hate learning someone else's code. No one writes perfect code because perfection is so subjective. Find me any real-world application and I can give you a damning indictment and rationale for doing a from-scratch rewrite.
Whether you ultimately rewrite from scratch or not, beginning a refactoring phase now is a good way to both really sit down and understand the problem so that the rewrite will go more smoothly if truly called for, as well as giving the existing codebase an honest look to really see if a rewrite's needed.
To actually scrap and start over?
When the current code doesn't do what you would like it to do, and would be cost prohibitive to change.
I'm sure someone will now link Joel's article about Netscape throwing their code away and how it's oh-so-terrible and a huge mistake. I don't want to talk about it in detail, but if you do link that article, before you do so, consider this: the IE engine, the engine that allowed MS to release IE 4, 5, 5.5, and 6 in quick succession, the IE engine that totally destroyed Netscape... it was new. Trident was a new engine after they threw away the IE 3 engine because it didn't provide a suitable basis for their future development work. MS did that which Joel says you must never do, and it is because MS did so that they had a browser that allowed them to completely eclipse Netscape. So please... just meditate on that thought for a moment before you link Joel and say "oh you should never do it, it's a terrible idea".
A rule of thumb I've found useful is that if given a code base, if I have to re-write more than 25% of the code to make it work or modify it based upon new requirements, you may as well re-write it from scratch.
The reasoning is that you can only patch a body of code so far; beyond a certain point, it's quicker to do over.
There's an underlying assumption that you have a mechanism (such as thorough unit and/or system tests) that will tell you whether your re-written version is functionally equivalent (where it needs to be) as the original.
If it requires more time to read and understand the code (if that is even possible)
than it would to rewrite the entire application, I say scrap it and start over.
Be very carefull with this:
Are you sure you aren't just being lazy and not bothering to read the code
Are you being arrogant about the great code you will write compared to the rubbish anyone else produced.
Remember tested-working code is worth a lot more than imaginary yet-to-be-written code
In the words of our estemed host and overlord, Joel - things you should never do,
it's not always wrong to abandon working code - but you have to be sure about the reason.
I saw an application re-architected within 2 years of its introduction into production, and others rewritten in different technologies (one was C++ - now Java). Both efforts were were not, to my mind, successful.
I prefer a more evolutionary approach to bad software. If you can "componentize" your old app such that you can introduce your new requirements and interface with the old code, you can ease yourself into the new environment without having to "sell" the zero-value (from a biz perspective) investment in rewriting.
Suggested approach - write unit tests for the functionality with which you wish to interface to 1) ensure the code behaves as you expect and 2) provide a safety net for any refactoring that you may wish to do on the old base.
Bad code is the norm. I think IT gets a bad rap from business for favoring rewrites/rearchitecting/etc. They pay the money and "trust" us (as an industry) to deliver solid, extensible code. Sadly, business pressures frequently result in shortcuts that make the code unmaintainable. Sometimes it's bad programmers... sometimes bad situations.
To answer your rephrased question... can code maintenance costs ever exceed rewriting costs... the answer is clearly yes. I don't see anything in your examples, however, that lead me to believe this is your case. I think those issues can be addressed with tests and refactoring.
In terms of business value, I would think it's extremely rare that a real case can be made for a rewrite due solely to the internal state of the code. If the product's customer-facing and is currently live and bringing in money (i.e. is not a mothballed or unreleased product), then consider that:
You already have customers using it. They're familiar with it, and might have built some of their own assets around it. (Other systems that interface to it; products based on it; processes they'd have to change; staff they'd maybe have to retrain). All of this costs the customer money.
Re-writing it might cost less in the long term than making difficult changes and fixes. But you can't quantify that yet, unless your app is no more complex than Hello World. And a re-write means a re-test and a redeploy, and probably an upgrade path for your customers.
Who says the re-write will be any better? Can you honestly say your firm is writing sparkly code now? Have the practices that turned the original code to spaghetti been corrected? (Even if the main culprit was a single developer, where were his peers and management, ensuring quality through reviews, testing, etc.?)
In terms of technical reasons, I'd suggest it could be time for a major rewrite if the original has some technical dependencies that have become problematic. e.g. a third party dependency that's now out of support, etc.
In general though, I think the most sensible move is to refactor piece by piece (very small pieces if it's really that bad), and improve the internal architecture incrementally rather than in one big drop.
Two threads of thought on this one: Do you have the original requirements? Do you have confidence that the original requirements are accurate? What about test plans or unit tests? If you have those things in place it might be easier.
Putting on my customer hat, does the system work or is it unstable? If you've got something that's unstable you've got an argument to change; otherwise you're best of refactoring it bit by bit.
I think the line in the sand is when basic maintenance is taking 25% - 50% longer than it should. There comes a time when maintaining legacy code becomes too costly. A number of factors contribute to the final decision. Time and cost being the most important factors I think.
If there are clean interfaces and you can cleanly delineate module boundaries, then it might be worth refactoring it module by module or layer by layer in order to allow you to migrate existing customers forward into cleaner more stable codebases, and over time, after you've refactored every module, you will have rewritten everything.
But, based on the codereview, doesn't sound like there would be any clean boundaries.
I wonder if the people who vote for scrapping and starting over have ever successfully refactored a large project, or at least seen a large project in poor condition that they think could use a refactoring?
If anything, I err on the opposite side: I've seen 4 large projects that were a mess, that I advocated refactoring as opposed to rewriting. On a couple, there was barely a single line of original code that remained, and major interfaces changed in significant ways, but the process never involved the entire project failing to function as well as it originally did, for any more than a week. (And top-of-trunk was never broken).
Perhaps a project exists that is so severely broken that to attempt to refactor it would be doomed to failure, or perhaps one of the previous projects I refactored would have been better served by a "clean re-write", but I'm not sure I'd know how to recognize it.
I agree with Martin. You really need to weigh the effort that will be involved in writing the app from scratch against the current state of the app and how many people use it, do they like it, etc. Often we may want to completely start from scratch, but the cost far outweighs the benefit. I come across bits of ugly looking code all the time, but I soon realize that some of these 'ugly' areas are really bug fixes and make the program work correctly.
I would try to consider the architecture of the system and see whether it is possible to scrap and rewrite specific well defined components without starting everything from scratch.
What would usually happen is that you can either do that (and then sell that to the customer/management), or that you find out that the code is such a horrible and tangled mess that you become even more convinced that you need a rewrite and have more convincing arguments for it (including: "if we engineer it right, we would never need to scrap the whole thing and do a third rewrite).
Slow maintenance would eventually cause that architectural drift that would make a rewrite more expensive later.
Scrap old code early and often. When in doubt, throw it out. The hard part is convincing non-technical folks of the cost-to-maintain.
So long as the value derived appears to be greater than the cost to operate and maintain, there's still positive value flowing from the software. The question surrounding a rewrite this: "will we get even more value from a rewrite?" Or alternatively "How much more value will we get from a rewrite?" How many person-hours of maintenance will you save?
Remember, the rewrite investment is once only. The return on the rewrite investment lasts forever. Forever.
Focus the value question down to specific issues. You listed a bunch of them above. Stick with that.
"Will we get more value by reducing cost through
dropping the junk that we don't use
but still have to wade through?"
"Will we get more value from dropping the junk that's unreliable and breaks?"
"Will we get more value if we understand it -- not by documenting, but by replacing with something we built as a team?"
Do you homework. You'll have to confront the following show-stoppers.
These will originate somewhere in your executive foodchain from someone who'll respond as follows:
"Is it broken?" And when you say "It's not crashed as such," They'll say "It's not broke - don't fix it."
"You've done the code analysis, you understand it, you no longer need to fix it."
What's your answer to them?
That's only the first hurdle. Here's the worst possible situation. This doesn't always happen, but it does happen with alarming frequency.
Someone in your executive foodchain will have this thought:
"A rewrite doesn't create enough value. Rather than simply rewrite, let's expand it." The justification is that by creating enough value, users are more likely to buy in to the rewrite.
A project where scope is expanded -- artificially -- to add value is usually doomed.
Instead, do the smallest rewrite you can to replace the darn thing. Then expand to fit real needs and add value.
You can only give a definite yes to rewriting in case if you know completely how your application works (and by completely I mean it, not just having a general idea of how it should work) and you know more or less exactly how to make it better. Any other cases and it's a shot in the dark, it depends on too much things. Perhaps gradual refactoring would be safer if it is possible.
If possible, I typically would prefer to rewrite smaller portions of the code over time when I need to refactor a baseline. There are typically many smaller issues such as magic number, poor commenting, etc. that tend to make the code look worse than it actually is. So, unless the baseline is just awful, keep the code and just make improvements at the same time you are maintaining the code.
If refactoring requires a lot of work, I recommend laying out a small re-design plan/todo list that gives you a list of things to work on in order so that you can bring the baseline to a better state. Starting from scratch is always a risky move and you are not guaranteed that the code will be better when you are finished. Using this technique, you will always have a working system that improves over time.
Code with excessively high cyclomatic complexity (like over 100 in a large number of modules) is a good clue. Also, how many bugs does it have / KLOC? How critical are the bugs? How often are bugs introduced when bug fixes are made. If your answer is a lot (I cant remember norms right now), then a rewrite is warranted.
As early as possible. Whenever you get a premonition that your code is slowly turning into an ugly beast that is very likely to consume your soul and give you headaches, and you know the problem is in the underlying structure of the code (so any fix would be a hack, e.g. introduce a global variable), then it's time to start over.
For some reasons people don't like throwing away precious code, but if you feel your better off starting over, you are probably right. Trust your instinct and remember that it wasn't a waste of time, it taught you one more way of NOT approaching the problem. You could (should) always use a version control system so your baby is never really lost.
I do not have any experience with using metrics for this myself, but the
article
"Software Maintainability Metrics Models in Practice" discusses
more or less the same question asked here for two case studies they did.
It starts with the following editor's note:
In the past, when a maintainer
received new code to maintain, the
rule-of-thumb was "If you have to
change more than 40 percent of someone
else's code, you throw it out and
start over." The Maintainability Index
[MI] addressed here gives a much more
quantifiable method to determine when
to "throw it out and start over." This
work was sponsored by the U.S. Air
Force Information Warfare Center and
the U.S. Department of Energy [DOE],
Idaho Field Office, DOE Contract No.
DE-AC07-94ID13223.)
I think the rule was...
The first version is always a throw away
So, if you learned your lesson(s), or his/her lessons, then you can go ahead and write it fresh now that you understand your problem domain better.
Not that there aren't parts that can/should be kept. Tested code is the most valuable code, so if it isn't deficient in any real way other than style, no reason to toss it all out.
When is it good (if ever) to scrap production code and start over?
Never had to do this, but logic would dictate (to me, anyway) that once you pass the inflection point where you're spending more time reworking and fixing bugs in the existing code base than you are adding new functionality, it's time to trash the old stuff and get a fresh start.
If it requires more time to read and understand the code (if that is even possible) than it would to rewrite the entire application, I say scrap it and start over.
I have never completely thrown out code. Even when going from a foxpro system to a c# system.
If the old system worked then why just throw it out?
I have come across a few really bad system. Threads being used where not needed. Horrible inheritance and abuse of interfaces.
It is best to understand what the old code is doing and why it is doing it. Then change it so that it is not confusing.
Of course if the old code doesn't work. I mean can't even compile. Then you might be justified in just starting over. But how often does that actually happen?
Yes, it totally can happen. I've seen money be saved by doing it.
This is not a tech decision, it's a business decision. Code rewrites are long term gains, while "if it ain't totally broke..." is a short term gain. If you are in a first year startup that is focused on getting a product out the door, the answer is usually to just live with it. If you're in an established company, or the errors with the current systems are causing more workload, therefor more company money.. then they might go for it.
Present the problem as best as you can to your GM, use dollar values where you can. "I don't like dealing with it" means nothing. "It'll take twice the time to do everything until this is fixed" means a lot.
I think there are a number of issues here that depend largely on where you are at.
Is the software working well from a customer perspective? (If yes be very careful about changes). I would think there would be little point re-witting unless you were expanding the feature set if the system was working. And are you planning to expand the features and customer base of the software? If so then you have much more reason to change.
As much as anything just trying to understand some else's code even if well written can be difficult, when badly written I would imagine almost impossible. What you describe sounds like something that would be very difficult to expand.
I would take into consideration if the application does what it is intended to do, is required for you to ever make modifications, and are you confident that the app has been thoroughly tested in all scenarios that it will be used in.
Do not invest the time if the app does not need alterations. However, if it doesn't function as you need and you need to control the hours and time invested to make corrections, scrap it and re-write to the standards that your team can support. There's nothing worse than terrible code that you have to support / decipher but still have to live with. Remember, Murphy's Law says it will 10 at night when you'll have to make things work, and that is never productive.
Production code always has some value. The only case where I would truly throw it all out and start again is if we determine the intellectual property is irrevocably contaminated. For example if someone brought large amounts of code from a previous employer, or a large percentage of the code was ripped from a GPLd codebase.
I'm going to post this book every time I see a discussion on Refactoring. Everyone should read "Working Effectively with Legacy Code" by Michael Feathers. I found it to be an excellent book - if nothing else, it's a fun read, and motivational.
When the code has reached a point that is not maintainable or extensible anymore. Is full of short-term hacky fixes. It has lots of coupling. It has long (100+lines) methods. It has database access in the UI. It generates a lot of random, impossible to debug errors.
Bottom line: When maintaining it is more expensive (i.e. takes longer) than rewriting it.
I used to believe in just re-write from scratch, but it is wrong.
http://www.joelonsoftware.com/articles/fog0000000069.html
Changed my mind.
What I would suggested is figuring out a way to properly refactor the code. Keep all existing functionality and test as you go. We have all seen horrible code bases, but it is important to keep the knowledge over time you application has.
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When coding, what in your experience is a better approach?
Break the problem down into small enough pieces and then implement each piece.
Break the problem down, but then implement using a top-down approach.
Any other?
I tend to design top-down and implement bottom-up.
For implementation, building the smallest functional pieces and assembling them into the higher-level structures seems to be what works best for me. But, for design, I need to start from the overall picture and break it down to determine what those pieces will be.
Here's what I do:
Understand the domain first. Understand the problem to be solved. Make sure you and the customer (even if that customer is you!) are on the same page as to what problem is to be solved.
Then a high level solution is proposed to the problem and from that, the design will turn into bubbles or bullets on a page or whatever, but the point is that it will shake out into components that can be designed.
At that point, I write tests for the yet-to-be written classes and then flesh out the classes to pass those tests.
I use a test-first approach and build working, tested components. That is what works for me. When the component interfaces are known and the 'rules' are known for how they talk to each other and provide services to each other, then it becomes generally a straightforward 'hook everything together' exercise.
That's how I do it, and it has worked well for me.
You might want to look over the Agile Manifesto. Top down and bottom up are predicated on Built It All At Once design and construction.
The "Working software over comprehensive documentation" means the first thing you build is the smallest useful thing you can get running. Top? Bottom? Neither.
When I was younger, I worked on projects that were -- by contract -- strictly top down. This doesn't work. Indeed, it can't work. You get mountains of redundant design and code as a result. It was not a sound approach when applied mindlessly.
What I've noticed is that the Agile approach -- small pieces that work -- tends to break the problem down to parts that can be grasped all at once. The top-down/bottom-up no longer matters as much. Indeed, it may not matter at all.
Which leads do: "How do you decompose for Agile development?" The trick is to avoid creating A Big Thing that you must then decompose. If you analyze a problem, you find actors trying to accomplish use cases and failing because they don't have all the information, or they don't have it in time, or they can't execute their decisions, or something like that.
Often, these aren't Big Things that need decomposition. When they are, you need to work through the problem in the Goals Backward direction. From Goals to things that enable you to make that goal to things that enable the enablers, etc. Since goals are often Big Things, this tends to be Top Down -- from general business goal to detailed business process and step.
At some point, we overview these various steps that lead to the goals. We've done the analysis part (breaking things down). Now comes the synthesis part: we reassemble what we have into things we can actually build. Synthesis is Bottom Up. However, let's not get carried away. We have several points of view, each of which is different.
We have a model. This is often built from details into a larger conceptual model. Then, sometimes decomposed again into a model normalized for OLTP. Or decomposed into a star schema normalized for OLAP. Then we work back up to create a ORM mapping from the normalized model. Up - Down - Up.
We have processing. This is often built from summaries of the business processes down into details of processing steps. Then software is designed around the steps. Then the software is broken into classes and methods. Down - Up - Down.
[Digression. With enlightened users, this decomposition defines new job titles and ways of working. With unenlightened users, the old jobs stay and we write mountains of documentation to map old jobs onto new software.]
We have components. We often look at the pieces, look at what we know about available components, and do a kind of matching. This is the randomest process; it's akin to the way crystals form -- there are centers of nucleation and the design kind of solidifies around those centers. Web Services. Database. Transaction Management. Performance. Volume. Different features that somehow help us pick components that implement some or all of our solution. Often feels bottom-up (from feature to product), but sometimes top-down ("I'm holding a hammer, call everything a nail" == use the RDBMS for everything.)
Eventually we have to code. This is bottom up. Kind of. You have to define a package structure. You have to define classes as a whole. That part was top down. You have to write methods within the classes. I often do this bottom-up -- rough out the method, write a unit test, finish the method. Rough out the next method, write a unit test, finish the method.
The driving principle is Agile -- build something that works. The details are all over the map -- up, down, front, back, data, process, actor, subject area, business value.
Yes. Do all of those things.
It may seem sarcastic (sorry, I revert to form), but this really is a case where there is no right answer.
Also in the agile way, write your test(s) first!
Then all software is a continual cycle of
Red - the code fails the test
Green - the code passes the test
Refactor - code improvements that are intention-preserving.
defects, new features, changes. It all follows the same pattern.
Your 2nd option is a reasonable way to go. If you break the problem down into understandable chunks, the top down approach will reveal any major design flaws before you implement all the little details. You can write stubs for lower level functionality to keep everything hanging together.
I think there's more to consider than top- verses bottom-down design. You obviously need to break the design up into manageable units of work but you also need to consider prioritisation etc. And in an iterative development project, you will often redefine the problem for the next iteration once you've delivered the solution for the previous one.
When designing, I like to do middle-out. I like to model the domain, then design out the classes, move to the database and UI from there. If there are specific features that are UI-based or database-based, I may design those up front as well.
When coding, I generally like to do bottom-up (database first, then business entities, then UI) if at all possible. I find it is a lot easier to keep things straight with this method.
I believe that with good software designers (and in my opinion all software developers should also be software designers at some level), the magic is in being able to do top-down and bottom-up simultaneously.
What I was "schooled" to do by my mentors is start by very brief top-down to understand the entities involved, then move to bottom-up to figure out the basic elements I want to create, then to back up and see how I can go one level down, knowing what I know about the results of my bottom up, and so forth until "they meet in the middle".
Hope that helps.
Outside-in design.
You start with what you're trying to achieve at the top end, and you know what you've got to work with at the bottom end. Keep working both ends until they meet in the middle.
I sort of agree with all of the people saying "neither", but everyone falls somewhere on the spectrum.
I'm more of a top-down kind of guy. I pick one high level feature/point/whatever and implement it as a complete program. This lets me sketch out a basic plan and structure within the confines of the problem domain.
Then I start with another feature and refactor out everything from the original that can be used by the second into new, shared entities. Lather, rinse, repeat until application is complete.
However, I know a lot of people who are bottom up guys, who hear a problem and start thinking about all the support subsystems that they could need to build the application on top of it.
I don't believe either approach is wrong or right. They both can achieve results. I even try and find bottom up guys to work with, as we can attack the problem from two different perspectives.
Both are valid approaches. Sometimes one just "feels" more natural than the other. However, there is one big problem: some mainstream languages and especially their frameworks and libraries really heavily on IDE support, such as syntax highlighting, background type checking, background compilation, intelligent code completion, IntelliSense and so on.
However, this doesn't work with top-down coding! In top-down coding, you constantly use variables, fields, constants, functions, procedures, methods, classes, modules, traits, mixins, aspects, packages and types that you haven't implemented yet! So, the IDE will constantly yell at you because of compile errors, there will be red squiggly lines everywhere, you will get no code completion and so on. So, the IDE pretty much prohibits you from doing top-down coding.
I do a variant of top-down. I tend to try and do the interface first - I then use that as my list of features. What's good about this version is, it still works with IDE that would otherwise complain. Just comment out the one function call to what's not yet been implemented.