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One of the most unpleasant (and unfortuantely most frequent) situations I am confronted with in my all day life as a developer is that I have to fix bugs or add features into code that is badly designed. Now as a good craftsman I would like to leave the code in a better state than I found it. Often new features can not be implemented if I do not refactor the design. Well - they could, but that would make the code even worse.
Unfortunately this is exactly what I tend to have a hard time with. I feel that if there is one thing that is hard, it is to refactor bad code, especially when you have deadlines. Touching bad and complex code that more or less works is scary. As a result I introduce even more clutter when I hack a new feature into the code without modifiying existing code.
Now my question is How can I learn to cope with bad code? How can I learn to understand huge codebases and then refactor parts of it without breaking stuff that already worked and without exceeding the deadline? Is there any literature you can recommend? Do you have any general tips for me?
General tip:
if (it is working)
Do (not touch it);
else
{
Make (as few modifications as possible)
Or (it will stop working at all);
}
This is experience of generations.
Michael Feathers wrote a good book about this subject exactly.
Working Effectively with Legacy Code.
Another great book is by Martin Fowler, Kent Beck and others:
Refactoring: Improving the Design of Existing Code.
Refactoring needs the safety harness of a unit test suite to remove that "Have I broken it?" feeling. Covering the bad code in a blanket of tests will help you whilst you strive for good clean code.
Pex is a tool that I find useful (if you are in the .NET world) for creating tests for legacy code.
Legacy code == code without tests!
When I have to deal with adding functionality to bad code, my usual approach is:
Write automated tests for every important feature that must work (as most bad code doesn't have any tests).
Do code changes.
Make sure the tests are still working.
That give you at least some confidence that you didn't break everything. As for how to learn coping with bad code, I guess it's just about experience.
Well, if you're going to refactor large amounts of code in a project I'd recommend using some decent version control, so you can branch and fall back easily. Given, this is probably is an open door, but crucial imo.
Furthermore, before you start getting in to complex OO, try breaking methods and functions into smaller ones. Ensuring some level of atomicity in each of the functions, which makes the code alot easier to maintain, read and manage.
It's all about the small stuff, break it down into logical units of operation, I'm doing a refactor action on a 1k lines method. It does al sorts of fancy stuff.
My first goal is to get as much stuff out of it in smaller pieces, when that's done I'll start thinking about a better OO design, which is much easier because I've a much better grasp on things.
Aspirin works good too.
I am currently in this situation. My approach is to answer some questions before touching the code:
Is the code really that bad? If yes, what are the common errors? ==> maybe concentrate on those first
What is the main runtime flow in the code? Maybe you can discard quite a few constructs from it.
Try to layer/modularize the code without changing it. This leads to some reduction of interdependencies
Try to poke the code with tests. If the code base is entangled beyond hope: use something like PowerMock to simulate objects that are not (yet) in need of change
Have an integration environment available, in which you can test changes in a production near environment.
Don't shy away to rewrite parts of the code base. But try to not implement too much new stuff in it
Try to team up, discuss designs, principles, solutions
This is tough work, and nobody will thank you for it. Be proud of small improvements and enjoy a good work done :)
I think that it is always good to have a general idea of how everything works in the software you are developing/improving. That's where the design documents and other documents made after or during the development process come in. I believe that if someone before you has not done proper documentation, then at least you should write a couple of lines somewhere about what you experience throughout your development process. I usually use OneNote or other stuff to write notes about what I encounter, and usually keep listing things which I feel would require refactoring. And if there is some downtime during the project, I usually go back to that list and try to improve things bit by bit.
So basically, if someone before you hasn't done it right, it would be good if at least you could help reduce the problems for any other developer who would come across the same code.
Refactoring: Improving the Design of Existing Code
It depends on number of factors but the most important is if you have authority to modify it.
In case you do, refactor it. For example, rename classes/functions/variables. Extract and generalize functionalities. See Refactoring: Improving the Design of Existing Code (Bible for the subject).
Before you begin doing that ensure that code is in a proper version control (VC) and have a good set of test cases. VC let you roll back and test cases help catching unexpected side-effects.
I suggest Distributed Version Control like Mercurial/Bazaar and Git because it is very refactoring is not exactly structured like adding features.
If there were no tests (common), you must create them. Read Working Effectively With Legacy Code. Especially about "Seal point" (not about Siamese cat :p).
In case you don't create a wrapper API that is cleaner.
For example:
Old code ====================
const ACT_SHOW = 'show';
const ACT_HIDE = 'hide';
function int DoThing(Object $Obj, Stirng $Action, Object $Param1, Object $Param1) {
....;
}
Added code ==================
enum Actions {
show, hide;
};
class ActionDoer {
private obj;
ActionDoer($Object) {
this.obj = $Object;
}
function int act(Actions $Action, $Param1, $Param1) {
this.act($Action.toString(), $Param1, $Param1) ;
}
function int act(String $Action, $Param1, $Param1) {
DoThing(this.obj, $Action, $Param1, $Param1) ;
}
function int show() {
this.act(Actions.show, null, null);
}
function int hide(Color $ToBGColor, long $FadeTime) {
this.act(Actions.hide, $ToBGColor, $FadeTime);
}
}
This way, the old code is not touched and the extension can be done using the new code. Good example of this method is jQuery where the old (default) way of accessing DOM is painful.
Hope this helps.
Related
I'm running a refactoring code dojo for some coworkers who asked how refactoring and patterns go together, and I need a sample code base. Anyone know of a good starting point that isn't to horrible they can't make heads or tails of the code, but can rewrite their way to something useful?
I would actually suggesting refactoring some of your and your coworkers' code.
There are always places that an existing codebase can be refactored, and the familiarity with the existing code will help make it feel more like a useful thing and less like an exercise. Find something in your company's code to use as an example, if possible.
Here are some codes, both the original and the refactored version, so you can prepare your kata or simply compare the results once the refactoring is performed:
My books have both shorter examples and a longer, actually a book long example. Code is free to download.
VB Code Examples
C# Code Examples
A nice example from Refactoring Workbook
There are a lot of examples on the internet of simple games like Tic-Tac-Toe or Snake that have a lot of smells but are simple enough to start with refactoring.
The first chapter in Martin Fowler "Refactoring" is a good starting point to refactoring. I understood most of the concepts when one of my teachers at school used this example.
What is the general knowledge level of your coworkers?
Something basic as code duplication should be easy to wrap their heads around. Two pieces of (nearly) identical code that can be refactored into a reusable method, class, whatever. Using a (past) example from your own codebase would be good.
I would recommend you to develop a simple example project for a specific requirement.
Then you add one more requirement and make changes to the existing classes . You keep on doing this and show them how you are finding it difficult to make each change when the code is not designed properly. This will make them realize easily because, this is what those ppl will be doing in their day to day work. Make them realize that , if patterns and principles are not followed from beginning, how are they going to end up in mess at the end.
When they realize that,then you start from scratch or refactor the existing messed up code .Now add a requirement and make them realize that it is easy to make a change in the refactored code, so that you need to test only a few classes. One change would not affect others and so on.
You could use the computer ,keyboard and printer class as an example. Add requirements like, you will be wanting the computer to read from mouse , then one more requirement can be like your computer would want to save it in hard disk than printing. Finally your refactored code should be like, your computer class should depend on abstract input device class and output device class. And your keyboard class should inherit from Inputdevice class.
Clean Code: A Handbook of Agile Software Craftsmanship by Robert C. Martin considers refactoring.
I'm loving Refactoring Guru examples.
In there you can find design patterns examples too.
Refactoring is non-functional requirement when code perform correct functionality for which it is designed however difficult to debug, requires more effort to maintain and some performance bottleneck. Refactoring is to change to be easily maintainable, good readability and improve efficiency.
Thus we need to focus on criteria to make code more readable, easy to maintain.
Its obvious that having very large method/function might be difficult to understand.
Class depends on other hundreds of class make thing worst while debugging.
Code should be readable just like reading some workflow.
You can also use tools like sonar which can help you to identify critical criteria such as "Cyclomatic Complexity"
http://www.sonarsource.org/managing-cyclomatic-complexity-to-increase-maintainability/
You ask them to write code them self and check how tool does refactoring.
Apart from that, you can write code in eclipse and there is option available which does refactoring for you...
It's a bit dated (2003), but IBM has several refactoring examples (that work[ed?] in Eclipse) at http://www.ibm.com/developerworks/library/os-ecref/
What do you believe in? As an incomplete basis for a good product - would you prefer a mess of code that is horrible to look at but works perfectly for what its supposed to do, or a beautiful set of well organized classes (or something else if OO doesn't float your boat) but have buggy functionality that still needs a lot of work?
If you were just handed a project to improve and work towards completion, which would you prefer? And what do you put the emphasis on when starting a new project?
Well written code will be easier to debug. If the code is too messy, even if it has "no bugs" (unlikely) it will not be maintainable.
I prefer both. However, if I was going to be handed a project I would go with buggy but beautiful everytime.
If we're talking about abstractions, I'd prefer to have just a small base set of working features. While it might be nice to have a pre-built, working library on top of this, the user can always create greater functionality from that working base.
Maybe they don't look nice, but again, a user can always just create a wrapper to make things look nice. I vote function.
Real artists ship - so something, that is both beautiful and gets the job done. But when in doubt, err on the "gets the job done" side, even if it isn't perfection.
Duplicate
What are your hard rules about commenting?
A Developer I work with had some things to say about commenting that were interesting to me (see below). What is your personal approach/take on commenting?
"I don't add comments to code unless
its a simple heading or there's a
platform-bug or a necessary
work-around that isn't obvious. Code
can change and comments may become
misleading. Code should be
self-documenting in its use of
descriptive names and its logical
organization - and its solutions
should be the cleanest/simplest way
to perform a given task. If a
programmer can't tell what a program
does by only reading the code, then
he's not ready to alter it.
Commenting tends to be a crutch for
writing something complex or
non-obvious - my goal is to always
write clean and simple code."
"I think there a few camps when it
comes to commenting, the
enterprisey-type who think they're
writing an API and some grand
code-library that will be used for
generations to come, the
craftsman-like programmer that thinks
code says what it does clearer than a
comment could, and novices that write
verbose/unclear code so as to need to
leave notes to themselves as to why
they did something."
There's a tragic flaw with the "self-documenting code" theory. Yes, reading the code will tell you exactly what it is doing. However, the code is incapable of telling you what it's supposed to be doing.
I think it's safe to say that all bugs are caused when code is not doing what it's supposed to be doing :). So if we add some key comments to provide maintainers with enough information to know what a piece of code is supposed to be doing, then we have given them the ability to fix a whole lot of bugs.
That leaves us with the question of how many comments to put in. If you put in too many comments, things become tedious to maintain and the comments will inevitably be out of date with the code. If you put in too few, then they're not particularly useful.
I've found regular comments to be most useful in the following places:
1) A brief description at the top of a .h or .cpp file for a class explaining the purpose of the class. This helps give maintainers a quick overview without having to sift through all of the code.
2) A comment block before the implementation of a non-trivial function explaining the purpose of it and detailing its expected inputs, potential outputs, and any oddities to expect when calling the function. This saves future maintainers from having to decipher entire functions to figure these things out.
Other than that, I tend to comment anything that might appear confusing or odd to someone. For example: "This array is 1 based instead of 0 based because of blah blah".
Well written, well placed comments are invaluable. Bad comments are often worse than no comments. To me, lack of any comments at all indicates laziness and/or arrogance on the part of the author of the code. No matter how obvious it is to you what the code is doing or how fantastic your code is, it's a challenging task to come into a body of code cold and figure out what the heck is going on. Well done comments can make a world of difference getting someone up to speed on existing code.
I've always liked Refactoring's take on commenting:
The reason we mention comments here is that comments often are used as a deodorant. It's surprising how often you look at thickly commented code and notice that the comments are there because the code is bad.
Comments lead us to bad code that has all the rotten whiffs we've discussed in the rest of this chapter. Our first action is to remove the bad smells by refactoring. When we're finished, we often find that the comments are superfluous.
As controversial as that is, it's rings true for the code I've read. To be fair, Fowler isn't saying to never comment, but to think about the state of your code before you do.
You need documentation (in some form; not always comments) for a local understanding of the code. Code by itself tells you what it does, if you read all of it and can keep it all in mind. (More on this below.) Comments are best for informal or semiformal documentation.
Many people say comments are a code smell, replaceable by refactoring, better naming, and tests. While this is true of bad comments (which are legion), it's easy to jump to concluding it's always so, and hallelujah, no more comments. This puts all the burden of local documentation -- too much of it, I think -- on naming and tests.
Document the contract of each function and, for each type of object, what it represents and any constraints on a valid representation (technically, the abstraction function and representation invariant). Use executable, testable documentation where practical (doctests, unit tests, assertions), but also write short comments giving the gist where helpful. (Where tests take the form of examples, they're incomplete; where they're complete, precise contracts, they can be as much work to grok as the code itself.) Write top-level comments for each module and each project; these can explain conventions that keep all your other comments (and code) short. (This supports naming-as-documentation: with conventions established, and a place we can expect to find subtleties noted, we can be confident more often that the names tell all we need to know.) Longer, stylized, irritatingly redundant Javadocs have their uses, but helped generate the backlash.
(For instance, this:
Perform an n-fold frobulation.
#param n the number of times to frobulate
#param x the x-coordinate of the center of frobulation
#param y the y-coordinate of the center of frobulation
#param z the z-coordinate of the center of frobulation
could be like "Frobulate n times around the center (x,y,z)." Comments don't have to be a chore to read and write.)
I don't always do as I say here; it depends on how much I value the code and who I expect to read it. But learning how to write this way made me a better programmer even when cutting corners.
Back on the claim that we document for the sake of local understanding: what does this function do?
def is_even(n): return is_odd(n-1)
Tests if an integer is even? If is_odd() tests if an integer is odd, then yes, that works. Suppose we had this:
def is_odd(n): return is_even(n-1)
The same reasoning says this is_odd() tests if an integer is odd. Put them together, of course, and neither works, even though each works if the other does. Change it a bit and we'd have code that does work, but only for natural numbers, while still locally looking like it works for integers. In microcosm that's what understanding a codebase is like: tracing dependencies around in circles to try to reverse-engineer assumptions the author could have explained in a line or two if they'd bothered. I hate the expense of spirit thoughtless coders have put me to this way over the past couple of decades: oh, this method looks like it has the side effect of farbuttling the warpcore... always? Well, if odd crobuncles desaturate, at least; do they? Better check all the crobuncle-handling code... which will pose its own challenges to understanding. Good documentation cuts this O(n) pointer-chasing down to O(1): e.g. knowing a function's contract and the contracts of the things it explicitly uses, the function's code should make sense with no further knowledge of the system. (Here, contracts saying is_even() and is_odd() work on natural numbers would tell us that both functions need to test for n==0.)
My only real rule is that comments should explain why code is there, not what it is doing or how it is doing it. Those things can change, and if they do the comments have to be maintained. The purpose the code exists in the first place shouldn't change.
the purpose of comments is to explain the context - the reason for the code; this, the programmer cannot know from mere code inspection. For example:
strangeSingleton.MoveLeft(1.06);
badlyNamedGroup.Ignite();
who knows what the heck this is for? but with a simple comment, all is revealed:
//when under attack, sidestep and retaliate with rocket bundles
strangeSingleton.MoveLeft(1.06);
badlyNamedGroup.Ignite();
seriously, comments are for the why, not the how, unless the how is unintuitive.
While I agree that code should be self-readable, I still see a lot of value in adding extensive comment blocks for explaining design decisions. For example "I did xyz instead of the common practice of abc because of this caveot ..." with a URL to a bug report or something.
I try to look at it as: If I'm dead and gone and someone straight out of college has to fix a bug here, what are they going to need to know?
In general I see comments used to explain poorly written code. Most code can be written in a way that would make comments redundant. Having said that I find myself leaving comments in code where the semantics aren't intuitive, such as calling into an API that has strange or unexpected behavior etc...
I also generally subscribe to the self-documenting code idea, so I think your developer friend gives good advice, and I won't repeat that, but there are definitely many situations where comments are necessary.
A lot of times I think it boils down to how close the implementation is to the types of ordinary or easy abstractions that code-readers in the future are going to be comfortable with or more generally to what degree the code tells the entire story. This will result in more or fewer comments depending on the type of programming language and project.
So, for example if you were using some kind of C-style pointer arithmetic in an unsafe C# code block, you shouldn't expect C# programmers to easily switch from C# code reading (which is probably typically more declarative or at least less about lower-level pointer manipulation) to be able to understand what your unsafe code is doing.
Another example is when you need to do some work deriving or researching an algorithm or equation or something that is not going to end up in your code but will be necessary to understand if anyone needs to modify your code significantly. You should document this somewhere and having at least a reference directly in the relevant code section will help a lot.
I don't think it matters how many or how few comments your code contains. If your code contains comments, they have to maintained, just like the rest of your code.
EDIT: That sounded a bit pompous, but I think that too many people forget that even the names of the variables, or the structures we use in the code, are all simply "tags" - they only have meaning to us, because our brains see a string of characters such as customerNumber and understand that it is a customer number. And while it's true that comments lack any "enforcement" by the compiler, they aren't so far removed. They are meant to convey meaning to another person, a human programmer that is reading the text of the program.
If the code is not clear without comments, first make the code a clearer statement of intent, then only add comments as needed.
Comments have their place, but primarily for cases where the code is unavoidably subtle or complex (inherent complexity is due to the nature of the problem being solved, not due to laziness or muddled thinking on the part of the programmer).
Requiring comments and "measuring productivity" in lines-of-code can lead to junk such as:
/*****
*
* Increase the value of variable i,
* but only up to the value of variable j.
*
*****/
if (i < j) {
++i;
} else {
i = j;
}
rather than the succinct (and clear to the appropriately-skilled programmer):
i = Math.min(j, i + 1);
YMMV
The vast majority of my commnets are at the class-level and method-level, and I like to describe the higher-level view instead of just args/return value. I'm especially careful to describe any "non-linearities" in the function (limits, corner cases, etc) that could trip up the unwary.
Typically I don't comment inside a method, except to mark "FIXME" items, or very occasionally some sort of "here be monsters" gotcha that I just can't seem to clean up, but I work very hard to avoid those. As Fowler says in Refactoring, comments tend to indicate smally code.
Comments are part of code, just like functions, variables and everything else - and if changing the related functionality the comment must also be updated (just like function calls need changing if function arguments change).
In general, when programming you should do things once in one place only.
Therefore, if what code does is explained by clear naming, no comment is needed - and this is of course always the goal - it's the cleanest and simplest way.
However, if further explanation is needed, I will add a comment, prefixed with INFO, NOTE, and similar...
An INFO: comment is for general information if someone is unfamiliar with this area.
A NOTE: comment is to alert of a potential oddity, such as a strange business rule / implementation.
If I specifically don't want people touching code, I might add a WARNING: or similar prefix.
What I don't use, and am specifically opposed to, are changelog-style comments - whether inline or at the head of the file - these comments belong in the version control software, not the sourcecode!
I prefer to use "Hansel and Gretel" type comments; little notes in the code as to why I'm doing it this way, or why some other way isn't appropriate. The next person to visit this code will probably need this info, and more often than not, that person will be me.
As a contractor I know that some people maintaining my code will be unfamiliar with the advanced features of ADO.Net I am using. Where appropriate, I add a brief comment about the intent of my code and a URL to an MSDN page that explains in more detail.
I remember learning C# and reading other people's code I was often frustrated by questions like, "which of the 9 meanings of the colon character does this one mean?" If you don't know the name of the feature, how do you look it up?! (Side note: This would be a good IDE feature: I select an operator or other token in the code, right click then shows me it's language part and feature name. C# needs this, VB less so.)
As for the "I don't comment my code because it is so clear and clean" crowd, I find sometimes they overestimate how clear their very clever code is. The thought that a complex algorithm is self-explanatory to someone other than the author is wishful thinking.
And I like #17 of 26's comment (empahsis added):
... reading the code will tell you exactly
what it is doing. However, the code is
incapable of telling you what it's
supposed to be doing.
I very very rarely comment. MY theory is if you have to comment it's because you're not doing things the best way possible. Like a "work around" is the only thing I would comment. Because they often don't make sense but there is a reason you are doing it so you need to explain.
Comments are a symptom of sub-par code IMO. I'm a firm believer in self documenting code. Most of my work can be easily translated, even by a layman, because of descriptive variable names, simple form, and accurate and many methods (IOW not having methods that do 5 different things).
Comments are part of a programmers toolbox and can be used and abused alike. It's not up to you, that other programmer, or anyone really to tell you that one tool is bad overall. There are places and times for everything, including comments.
I agree with most of what's been said here though, that code should be written so clear that it is self-descriptive and thus comments aren't needed, but sometimes that conflicts with the best/optimal implementation, although that could probably be solved with an appropriately named method.
I agree with the self-documenting code theory, if I can't tell what a peice of code is doing simply by reading it then it probably needs refactoring, however there are some exceptions to this, I'll add a comment if:
I'm doing something that you don't
normally see
There are major side effects or implementation details that aren't obvious, or won't be next year
I need to remember to implement
something although I prefer an
exception in these cases.
If I'm forced to go do something else and I'm having good ideas, or a difficult time with the code, then I'll add sufficient comments to tmporarily preserve my mental state
Most of the time I find that the best comment is the function or method name I am currently coding in. All other comments (except for the reasons your friend mentioned - I agree with them) feel superfluous.
So in this instance commenting feels like overkill:
/*
* this function adds two integers
*/
int add(int x, int y)
{
// add x to y and return it
return x + y;
}
because the code is self-describing. There is no need to comment this kind of thing as the name of the function clearly indicates what it does and the return statement is pretty clear as well. You would be surprised how clear your code becomes when you break it down into tiny functions like this.
When programming in C, I'll use multi-line comments in header files to describe the API, eg parameters and return value of functions, configuration macros etc...
In source files, I'll stick to single-line comments which explain the purpose of non-self-evident pieces of code or to sub-section a function which can't be refactored to smaller ones in a sane way. Here's an example of my style of commenting in source files.
If you ever need more than a few lines of comments to explain what a given piece of code does, you should seriously consider if what you're doing can't be done in a better way...
I write comments that describe the purpose of a function or method and the results it returns in adequate detail. I don't write many inline code comments because I believe my function and variable naming to be adequate to understand what is going on.
I develop on a lot of legacy PHP systems that are absolutely terribly written. I wish the original developer would have left some type of comments in the code to describe what was going on in those systems. If you're going to write indecipherable or bad code that someone else will read eventually, you should comment it.
Also, if I am doing something a particular way that doesn't look right at first glance, but I know it is because the code in question is a workaround for a platform or something like that, then I'll comment with a WARNING comment.
Sometimes code does exactly what it needs to do, but is kind of complicated and wouldn't be immediately obvious the first time someone else looked at it. In this case, I'll add a short inline comment describing what the code is intended to do.
I also try to give methods and classes documentation headers, which is good for intellisense and auto-generated documentation. I actually have a bad habit of leaving 90% of my methods and classes undocumented. You don't have time to document things when you're in the middle of coding and everything is changing constantly. Then when you're done you don't feel like going back and finding all the new stuff and documenting it. It's probably good to go back every month or so and just write a bunch of documentation.
Here's my view (based on several years of doctoral research):
There's a huge difference between commenting functions (sort of a black box use, like JavaDocs), and commenting actual code for someone who will read the code ("internal commenting").
Most "well written" code shouldn't require much "internal commenting" because if it performs a lot then it should be broken into enough function calls. The functionality for each of these calls is then captured in the function name and in the function comments.
Now, function comments are indeed the problem, and in some ways your friend is right, that for most code there is no economical incentive for complete specifications the way that popular APIs are documented. The important thing here is to identify what are the "directives": directives are those information pieces that directly affect clients, and require some direct action (and are often unexpected). For example, X must be invoked before Y, don't call this from outside a UI thread, be aware that this has a certain side effect, etc. These are the things that are really important to capture.
Since most people never read full function documentations, and skim what they do read, you can actually increase the chances of awareness by capturing only the directives rather than the whole description.
I comment as much as needed - then, as much as I will need it a year later.
We add comments which provide the API reference documentation for all public classes / methods / properties / etc... This is well worth the effort because XML Documentation in C# has the nice effect of providing IntelliSense to users of these public APIs. .NET 4.0's code contracts will enable us to improve further on this practice.
As a general rule, we do not document internal implementations as we write code unless we are doing something non-obvious. The theory is that while we are writing new implementations, things are changing and comments are more likely than not to be wrong when the dust settles.
When we go back in to work on an existing piece of code, we add comments when we realize that it's taking some thought to figure out what in the heck is going on. This way, we wind up with comments where they are more likely to be correct (because the code is more stable) and where they are more likely to be useful (if I'm coming back to a piece of code today, it seems more likely that I might come back to it again tomorrow).
My approach:
Comments bridge the gap between context / real world and code. Therefore, each and every single line is commented, in correct English language.
I DO reject code that doesn't observe this rule in the strictest possible sense.
Usage of well formatted XML - comments is self-evident.
Sloppy commenting means sloppy code!
Here's how I wrote code:
if (hotel.isFull()) {
print("We're fully booked");
} else {
Guest guest = promptGuest();
hotel.checkIn(guest);
}
here's a few comments that I might write for that code:
// if hotel is full, refuse checkin, otherwise
// prompt the user for the guest info, and check in the guest.
If your code reads like a prose, there is no sense in writing comments that simply repeats what the code reads since the mental processing needed for reading the code and the comments would be almost equal; and if you read the comments first, you will still need to read the code as well.
On the other hand, there are situations where it is impossible or extremely difficult to make the code looks like a prose; that's where comment could patch in.
I just refactored some code that was in a different section of the class I was working on because it was a series of nested conditional operators (?:) that was made a ton clearer by a fairly simple switch statement (C#).
When will you touch code that isn't directly what you are working on to make it more clear?
I once was refactoring and came across something like this code:
string strMyString;
try
{
strMyString = Session["MySessionVar"].ToString();
}
catch
{
strMyString = "";
}
Resharper pointed out that the .ToString() was redundant, so I took it out. Unfortunately, that ended up breaking the code. Whenever MySessionVar was null, it wasn't causing the NullReferenceException that the code relied on to bump it down to the catch block. I know, this was some sad code. But I did learn a good lesson from it. Don't rapidly go through old code relying on a tool to help you do the refactoring - think it through yourself.
I did end up refactoring it as follows:
string strMyString = Session["MySessionVar"] ?? "";
Update: Since this post is being upvoted and technically doesn't contain an answer to the question, I figured I should actually answer the question. (Ok, it was bothering me to the point that I was actually dreaming about it.)
Personally I ask myself a few questions before refactoring.
1) Is the system under source control? If so, go ahead and refactor because you can always roll back if something breaks.
2) Do unit tests exist for the functionality I am altering? If so, great! Refactor. The danger here is that the existence of unit tests don't indicate the accuracy and scope of said unit tests. Good unit tests should pick up any breaking changes.
3) Do I thoroughly understand the code I am refactoring? If there's no source control and no tests and I don't really understand the code I am changing, that's a red flag. I'd need to get more comfortable with the code before refactoring.
In case #3 I would probably spend the time to actually track all of the code that is currently using the method I am refactoring. Depending on the scope of the code this could be easy or impossible (ie. if it's a public API). If it comes down to being a public API then you really need to understand the original intent of the code from a business perspective.
I only refactor it if tests are already in place. If not, it's usually not worth my time to write tests for and refactor presumably working code.
This is a small, minor antipattern but it so irritates me that whenever I find it, I expunge it immediately. In C (or C++ or Java)
if (p)
return true;
else
return false;
becomes
return p;
In Scheme,
(if p #t #f)
becomes
p
and in ML
if p then true else false
becomes
p
I see this antipattern almost exclusively in code written by undergraduate students. I am definitely not making this up!!
Whenever I come across it and I don't think changing it will cause problems (e.g. I can understand it enough that I know what it does. e.g. the level of voodoo is low).
I only bother to change it if there is some other reason I'm modifying the code.
How far I'm willing to take it depends on how confident I am that I won't break anything and how extensive my own changes to the code are going to be.
This is a great situation to show off the benefits of unit tests.
If unit tests are in place, developers can bravely and aggressively refactor oddly written code they might come across. If it passes the unit tests and you've increased readability, then you've done your good deed for the day and can move on.
Without unit tests, simplifying complex code that's filled with voodoo presents a great risk of breaking the code and not even knowing you've introduced a new bug! So most developers will take the cautious route and move on.
For simple refactoring I try to clean up deeply nested control structures and really long functions (more than one screen worth of text). However its not a great idea to refactor code without a good reason (especially in a big team of developers). In general, unless the refactoring will make a big improvement in the code or fix an egregious sin I try to leave well enough alone.
Not refactoring per-say but just as a matter of general housekeeping I generally do this stuff when I start work on a module:
Remove stupid comments
Comments that say nothing more than the function signature already says
Comments that are pure idiocy like "just what it looks like"
Changelogs at the top of the file (we have version control for a reason)
Any API docs that are clearly out-of-sync with the code
Remove commented-out chunks of code
Add version control tags like $Id$ if they are missing
Fix whitespace issues (this can be annoying to others though because your name shows up for a lot of lines in a diff even if all you did was change whitespace)
Remove whitespace at the end of the lines
Change tabs->spaces (for that is our convention where I work)
If the refactor makes the code much easier to read, the most common for me would be duplicate code, e.g. an if/else that only differs by the first/last commands.
if($something) {
load_data($something);
} else {
load_data($something);
echo "Loaded";
do_something_else();
}
More than (arguably) three or four lines of duplicate code always makes me think about refactoring. Also, I tend to move code around a lot, extracting the code I predict to be used more frequently into a separate place - a class with its own well-defined purpose and responsibilites, or a static method of a static class (usually placed in my Utils.* namespace).
But, to answer your question, yes, there are lot of cases when making the code shorter does not necessarily mean making it well structued and readable. Using the ?? operator in C# is another example. What you also have to think about are the new features in your language of choice - e.g. LINQ can be used to do some stuff in a very elegant manner but also can make a very simple thing very unreadable and overly complex. You need to weigh these two thing very carefully, in the end it all boils down to your personal taste and, mostly, experience.
Well, this is another "it depends" answer, but I am afraid it has to be.
I almost always break >2 similar conditionals into a switch... most often with regards to enums. I will short a return instead of a long statement.
ex:
if (condition) {
//lots of code
//returns value
} else {
return null;
}
becomes:
if (!condition)
return null;
//lots of code..
//return value
breaking out early reduces extra indents, and reduces long bits of code... also as a general rule I don't like methods with more than 10-15 lines of code. I like methods to have a singular purpose, even if creating more private methods internally.
Usually I don't refactor the code if I'm just browsing it, not actively working on it.
But sometimes ReSharper points out some stuff I just can't resist to Alt+Enter. :)
I tend to refactor very long functions and methods if I understand the set of inputs and outputs to a block.
This helps readability no end.
I would only refactor the code that I come across and am not actively working on after going through the following steps:
Speak with the author of the code (not always possible) to figure out what that piece of code does. Even if it is obvious to me as to what the piece of code is doing, it always helps to understand the rationale behind why the author may have decided to do something in a certain way. Spending a couple of minutes talking about it would not only help the original author understand your point of view, it also builds trust within the team.
Know or find out what that piece of code is doing in order to test it after re-factoring (A build process with unit tests is very helpful here. It makes the whole thing quick and easy). Run the unit tests before and after the change and ensure nothing is breaking due to your changes.
Send out a heads up to the team (if working with others) and let them know of the upcoming change so nobody is surprised when the change actually occurs
Refactoring for the sake of it is one of the roots of all evil. Please don't ever do it. (Unit tests do somewhat mitigate this).
Is vast swaths of commented out code an antipattern? While not code specifically, (it's comments) I see a lot of this kind of behaviour with people who don't understand how to use source control, and who want to keep the old code around for later so they can more easily go back if a bug was introduced. Whenever I see vast swaths of code that are commented out, I almost always remove them in their entirety.
I try to refactor based on following factors:
Do I understand enough to know whats happening?
Can I easily revert back if this change breaks the code.
Will I have enough time to revert the change back if it breaks the build.
And sometimes, if I have enough time, I refactor to learn. As in, I know my change may break the code, but I dont know where and how. So I change it anyways to find out where its breaking and why. That way I learn more about the code.
My domain has been mobile software (cell phones) where most of the code resides on my PC and wont impact others. Since I also maintain the CI build system for my company I can run a complete product build (for all phones) on the refactored code to ensure it doesnt break anything else. But thats my personal luxury which you may not have.
I tend to refactor global constants and enumerations quite a bit if they can be deemed a low refactor risk. Maybe it's just be, but something like a ClientAccountStatus enum should be in or close to the ClientAccount class rather than being in a GlobalConstAndEnum class.
Deletion/updating of comments which are clearly wrong or clearly pointless.
Removing them is:
safe
version control means you can find them again
improves the quality of the code to others and yourself
It is about the only 100% risk free refactoring I know.
Note that doing this in structured comments like javadoc comments is a different matter. Changing these is not risk free, as such they are very likely to be fixed/removed but not dead certain guaranteed fixes as standard incorrect code comments would be.
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I've worked on a couple of projects where we spent a great deal of time discussing and writing elaborate coding standards covering everything from syntax layout to actual best practices. However, I have also found that these are rarely followed to the full extent. Many developers seem to hesitate to reject a code review based on coding standard violations alone. I.e. violations are committed to the repository on a regular basis.
My questions are: Do you have coding standards? What do they cover? Are they followed by everyone? And what do you do (if anything) to make sure everybody is following the standards?
I'm aware that there is a similar question here, but my concern is not so much how you could do it, but how you are actually going about it and what are the perceived benefits?
I've worked in places with barely-followed coding practices, and others where they're close to being enforced - or at least easily checked.
A few suggestions:
The most important thing is to get buy-in to the idea that consistency trumps your personal preferred style. There should be discussion of the coding standard both before and after it's instituted, but no-one should be allowed to just opt out of it.
Code reviews should be mandatory, with the checkin comment including the username of the reviewer. If you're using a suitably powerful SCM, consider not allowing checkins which don't have a valid reviewer name.
There should be a document which everyone knows about laying out the coding standards. With enough detail, you shouldn't get too much in the way of arguments.
Where possible, automate checking of the conventions (via Lint, CheckStyle, FXCop etc) so it's easy for both the committer and the reviewer to get a quick check of things like ordering import/using directives, whitespace etc.
The benefits are:
Primarily consistency - if you make it so that anyone can feel "at home" in any part of the codebase at any time, it gives you more flexibility.
Spreading best practice - if you ban public fields, mutable structs etc then no-one can accidentally plant a time bomb in your code. (At least, not a time bomb that's covered by the standard. There's no coding standard for perfect code, of course :)
EDIT: I should point out that coding standards are probably most important when working in large companies. I believe they help even in small companies, but there's probably less need of process around the standard at that point. It helps when all the developers know each other personally and are all co-located.
Do you have coding standards?
Yes, differs from project to project.
What does it cover?
Code(class, variable, method, constant), SQL naming and formatting convention
Is it being followed by everyone?
Yes, every new entrant in project could be asked to create a demo project following organization coding convention then it gets reviewed. This exercise makes developer feel at ease before starting real job.
And what do you do (if anything) to make sure everybody is following the standard?
Use StyleCop and FxCop to ensure they are religiously followed. It would show up as warning/error if code fails to comply with organization coding convention.
Visual Studio Team system has nice code anlysis and check-In policies which would prevent developers checking in code that does not comply
Hope, it helps
Thanks,
Maulik Modi
We take use of the Eclipse's save actions and formatters. We do have a suggested standard, but nobody is actually enforcing it, so there are some variations on what is actually formatted, and how.
This is something of a nuisance (for me), as various whitespace variations are committed as updates to the SVN repository...
StyleCop does a good job of enforcing coding layout practices and you can write custom rules for it if something isn't covered in the base rules that is important to you.
I think coding standards are very important. There is nothing more frustrating than trying to find the differences between two revisions of a file only to find that the whole file has been changed by someone who reformatted it all. And I know someone is going to say that that sort of practice should be stamped out, but most IDEs have a 'reformat file' feature (Ctrl-K Ctrl-D in Visual Studio, for example), which makes keeping your code layed out nicely much easier.
I've seen projects fail through lack of coding standards - the curly-brace wars at my last company were contributary to a breakdown in the team.
I've found the best coding standards are not the standards made up by someone in the team. I implemented the standards created by iDesign (click here) in our team, which gets you away from any kind of resentment you might get if you try to implement your own 'standard'.
A quick mention of Code Style Enforcer (click here) which is pretty good for highlighting non-compliance in Visual Studio.
I have a combination of personal and company coding standards that are still evolving to some extent. They cover code structure, testing, and various documents describing various bits of functionality.
As it evolves, it is being adopted and interpreted by the rest of my team. Part of what will happen ultimately is that if there is concensus on some parts then those will hold up while other parts may just remain code that isn't necessarily going to be up to snuff.
I think there may be some respect or professional admiration that act as a way of getting people to follow the coding standards where some parts of it become clear after it is applied, e.g. refactoring a function to be more readable or adding tests to some form, with various "light bulb moments" to borrow a phrase from Oprah.
Another part of the benefit is to see how well do others work, what kinds of tips and techniques do they have and how can one improve over time to be a better developer.
I think the best way to look at coding standards is in terms of what you hope to achieve by applying, and the damage that they can cause if mis-applied. For example, I see the following as quite good;
Document and provide unit tests that illustrate all typical scenarios for usage of a given interface to a given routine or module.
Where possible use the following container classes libraries, etc...
Use asserts to validate incoming parameters and results returned (C & C++)
Minimise scope of all variables
Access object members through methods
Use new and delete over malloc and free
Use the prescribed naming conventions
I don't think that enforcing style beyond this is a great idea, as different programmers are efficient using differing styles. Forcing programmers to change style can be counter productive and lead to lost time and reduced quality. Standards should be kept short and easy to understand.
Oh yes, I'm the coding standard police :) I just wrote a simple script to periodically check and fix the code (my coding standard is simple enough to implement that.) I hope people will get the message after seeing all these "coding convention cleanups" messages :)
We have a kind of 'loose' standard. Maybe because of our inability to have agreement upon some of those 'how many spaces to put there and there', 'where to put my open brace, after the statement or on the next line'.
However, as we have main developers for each of the dedicated modules or components, and some additional developers that may work in those modules, we have the following main rule:
"Uphold the style used by the main developer"
So if he wants to do 3 space-indentation, do it yourself also.
It's not ideal as it might require retune your editor settings, but it keeps the peace :-)
Do you have coding standards?
What does it cover?
Yes, it has naming conventions, mandatory braces after if, while ... , no warning allowed, recommendations for 32/64 bits alignment, no magic number, header guards, variables initialization and formatting rules that favor consistency for legacy code.
Is it being followed by everyone?
And what do you do (if anything) to make sure everybody is following the standard?
Mostly, getting the team agreement and a somewhat lightweight coding standard (less than 20 rules) helped us here.
How it is being enforced ?
Softly, we do not have coding standard cop.
Application of the standard is checked at review time
We have template files that provide the standard boilerplate
I have never seen a project fail because of lack of coding standards (or adherence to them), or even have any effect on productivity. If you are spending any time on enforcing them then you are wasting money. There are so many important things to worry about instead (like code quality).
Create a set of suggested standards for those who prefer to have something to follow, but leave it at that.
JTest by ParaSoft is decent for Java.
Our coding standards are listed in our Programmer's Manual so everyone can easily refer to them. They are effective simply because we have buy in from all team members, because people are not afraid to raise standards and style issues during code reviews, and because they allow a certain level of flexibility. If one programmer creates a new file, and she prefers to place the bracket on the same line as an if statement, that sets the standard for that file. Anyone modifying that file in the future must use the same style to keep things consistent.
I'll admit, when I first read the coding standards, I didn't agree with some of them. For instance, we use a certain style for function declarations that looks like this:
static // Scope
void // Type declaration
func(
char al, //IN: Description of al
intl6u hash_table_size, //IN/OUT: Description of hash_table_size
int8u s) //OUT: Description of s
{
<local declarations>
<statements>
}
I had never seen that before, so it seemed strange and foreign to me at first. My gut reaction was, "Well, that's dumb." Now that I've been here a while, I have adjusted to the style and appreciate how I can quickly comprehend the function declaration because everyone does it this way.