I'm refactoring one of my projects - a shopping cart. One of the tightly coupled areas of my code is the "Viewer" class - to generate information for the user to see, it often needs a combination of two or more of the following objects:
The store catalog.
The customer's order.
The customer's mailing information.
I can't really break up the display methods, for various reasons.
Martin Fowler's Refactoring identifies this as a "Long parameter list" smell. The relevant refactoring here is "Introduce parameter object." I am, however, hesitant to do that, as doing so would couple loosely related data. It would also lock me to a very narrow one-to-one relationship between those three objects - while that would work for my application as it is now, it makes no real-world sense. (As there is only one store catalog, there can be many "Customer mailing information" objects, and each of those may be related to many "Customer's order" objects).
Does anyone have any elegant solutions to this?
A parameter list of three parameters needs no refactoring. Start worrying when you reach, say, 8 or 10 parameters.
Try to name the thing that binds a catalog, an order, and an address. Start, maybe with CatalogOrderAddressTuple. Ugly, isn't it? Well, maybe as a utility class of your Viewer, it should just be an inner class, where you could get by with just Tuple - or Data. Still ugly.
It doesn't sound like these belong as actual fields to the Viewer - but explore what that would look like, how your code would change if each Viewer were simply constructed with the data on which it operates.
As ammoQ & Ryan Prior have said, this isn't much of a smell, but I'd say it's worth playing with some alternatives before giving up entirely.
As stated by ammoQ, looking for refactoring opportunities with so few parameters is stretching.
See also: KISS and YAGNI.
It seems to me that introducing a parameter object would have the opposite effect of locking you to a one-to-one relationship between those three objects.
If a single customer address is being passed around, and in the future someone decides to separate billing address and shipping address, then it would probably be simpler to add the new address to a parameter object, rather than add a new parameter up and down the call stack.
(This is just an example, of course. Ideally, the address information would exist separately in the order and customer objects, since all information on posted orders should be immutable, even if the customer's address changes. But that wasn't what you were asking about!)
Related
I'm currently working on an internationalisation project for a large web application - initially we're just implementing French but more languages will follow in time. One of the issues we've come across is how to display adjectives.
Let's take "Active" as an example. When we received translations back from the company we're using, they returned "Actif(ve)", as English "Active" translates to masculine "Actif" or feminine "Active". We're unsure of how to display this, and wondered if there are any well established conventions in the web development world.
As far as I see it there are three possible scenarios:
We know at development time which noun a given adjective is referring to. In this case we can determine and use the correct gender.
We're referring to a user, either directly ("you") or in the third person. Short of making every user have a gender, I don't see a better approach than displaying both, i.e. "Actif(ve)"
We are displaying the adjective in isolation, not knowing which noun it's referring to. For example in a table of data, some rows might be dealing with a masculine entity, some feminine.
Scenarios 2 and 3 seem to be the toughest ones. Does anyone have any experience handling these issues? Any tips would be appreciated!
This is complex, because we cannot imagine all the cases, and there is risk to go in "opinion based" answer, so I keep it short and generic.
Usually I prefer to give context in translation (for translator), e.g. providing template: _("active {user_name}" (so also the ordering will be correct if languages want different ordering).
Then you may need to change code and template into _("active {first_name_feminine}") and _("active {first_name_masculine}") (and possibly more for duals, trials, plurals, collectives, honorific, etc.). Note: check that the translator will not mangle the {} and the string inside. Usually you need specific export/import scripts. Or I add a note inside the string, and I quickly translate into English removing the note to the translator). Also this can be automated (be creative on using special Unicode characters which should not be used in normal text, to delimit such text).
But if you cannot know the gender, the Actif(ve) may be the polite version used in such language. You need a native speaker test, and changes back and forth.
I am writing an app that has a sign-up form. This article made me doubt everything I knew about human names. My question is: does a person's name necessarily have positive length? Or can I validate names in this way and be confident that I have not denied anyone their identity?
P.S.: one might ask why am I validating at all. The answer is that this is for a school project and proper validation is a part of the mark. The article above proves that person's name can be pretty much any string of positive length but I don't know if zero length is OK.
With all types of programming, you have to draw a distinction between what is meaningful in the real world, and what is meaningful for your software solution.
How the data is to be used will validate what type of validation is required.
For instance, if your software interfaces with a government API, and the government API requires a first name and surname, you should do the same.
If you're interacting with bank accounts, you may have a single string which represents that account name, which many or may not be a human name or not, but may have other constraints around length.
If the name is only to be used for display purposes, maybe there is no point to capture the name at all, and instead you should capture a preferred display name (which doesn't needlessly assume a certain number of name components).
When writing software, you should target to make as few assumptions as possible, unless those assumptions will cause an increase in complexity of your software solution. If the software requires people to have non-empty names, then you should validate at the border that this is true.
In addition, if you were my student, you would have already lost marks for conflating null, and an empty string. In this instance, null would represent you lack data about the name, and an empty string would indicate that user has specified that their name is empty.
Also, if you decide not to validate something, you should at least leave a comment to indicate that you thought of it. If you do something unusual, it's possible a future developer may come along and fix the "bug". In addition, this helps you avoid losing marks.
Is there a data structure within LiveCode that can be used as a "holder" for associated data, letting me handle it collectively? I come from a Java / Javascript / C background so I am looking for a Class or Struct sort of data structure.
I've found examples of Groups, which seem to have some of this functionality, but it feels a bit like I'm bending the language to meet my needs.
As a specific example, suppose I had an image field on my screen that would randomly display an image and, when pressed, play an associated sound clip. I'd expect to create a list of "structures" that contained the path to the image and the path to the associated sound clip, and use that data to populate the image field and to decide what sound clip to play.
Would a Group be the correct structure to use in this case? Or am I approaching this in a way that isn't really fitting with the way LiveCode works?
It takes a little getting used to, but the xTalk world is much simpler and more open than any ordinary procedural language. So much of what you once had to manage is no longer required.
So when splash21 said that you could store all your image and sound references in a custom property, he was really saying that the LiveCode environment contains intrinsic, high level functionality that makes these sorts of things instantly accessible, and the only thing required of you is to call for them, and they simply work.
The only way to appreciate this is to make a few simple programs, to really see what is possible. Make your application. Everything you mentioned can be accomplished with perhaps a dozen lines of code in a single handler. I recommend that you join the LiveCode use list and forums. The community is vibrant and eager to help, frequently with full blown solutions to specific problems, but more importantly, as guides and mentors to new users
Craig Newman
Arrays in LiveCode are actually associative arrays (like hash maps). A key is associated with a value. The value might be as well an array.
Chapter 5.5.7 of the User's Guide says
Array elements may contain nested or sub-elements, making them multi-dimensional.
This type of array is ideal for processing hierarchical data structures such as trees or
XML. To access a sub-element, simply declare it using an additional set of square
brackets.
put "ABC" into myVariable["myKeyName"][“aChildElement”]
see also
How to store pictures in a stack?
Dave- I'm hoping to get a struct-like container implemented in the near future. Meanwhile you can, as splash21 mentioned, use custom properties (or better yet, custom property sets) to do what you want. This will give you a pseudo-struct for each object and you can implement the file and sound specifications into the properties. And if you use that in conjunction with a behavior object you'll end up very close to a real inheritable class formation.
I am new at the idea of programming algorithms. I can work with simplistic ideas, but my current project requires that I create something a bit more complicated.
I'm trying to create a categorization system based on keywords and subsets of 'general' categories that filter down into more detailed categories that requires as little work as possible from the user.
I.E.
Sports >> Baseball >> Pitching >> Nolan Ryan
So, if a user decides they want to talk about "Baseball" and they filter the search, I would like to also include 'Sports"
User enters: "baseball"
User is then taken to Sports >> Baseball
Now I understand that this would be impossible without a living - breathing dynamic program that connects those two categories in some way. It would also require 'some' user input initially, and many more inputs throughout the lifetime of the software in order to maintain it and keep it up to date.
But Alas, asking for such an algorithm would be frivolous without detailing very concrete specifics about what I'm trying to do. And i'm not trying to ask for a hand out.
Instead, I am curious if people are aware of similar systems that have already been implemented and if there is documentation out there describing how it has been done. Or even some real life examples of your own projects.
In short, I have a 'plan' but it requires more user input than I really want. I feel getting more info on the subject would be the best course of action before jumping head first into developing this program.
Thanks
IMHO It isn't as hard as you think. What you want is called Tagging and you can do it Automatically just by setting the correlation between tags (i.e. a Tag can have its meaningful information plus its reation with other ones. Then, if user select a Tag well, you related that with others via looking your ADT collection (can be as simple as an array).
Tag:
Sport
Related Tags
Football
Soccer
...
I'm hoping this helps!
It sounds like what you want to do is create a tree/menu structure, and then be able to rapidly retrieve the "breadcrumb" for any given key in the tree.
Here's what I would think:
Create the tree with all the branches. It's okay if you want branches to share keys - as long as you can give the user a "choice" of "Multiple found, please choose which one... ?"
For every key in the tree, generate the breadcrumb. This is time-consuming, and if the tree is very large and updating regularly then it may be something better done offline, in the cloud, or via hadoop, etc.
Store the key and the breadcrumb in a key/value store such as redis, or in memory/cached as desired. You'll want every value to have an array if you want to share keys across categories/branches.
When the user selects a key - the key is looked up in the store, and if the resulting value contains only one match, then you simply construct the breadcrumb to take the user where you want them to go. If it has multiple, you give them a choice.
I would even say, if you need something more organic, say a user can create "new topic" dynamically from anywhere else, then you might want to not use a tree at all after the initial import - instead just update your key/value store in real-time.
I'm trying to use the ABPerson method searchElementForProperty:... to create a moderately complex search. In particular, I want to find the set of people who have an email address that ends with "foo.com", and are NOT part of the pre-populated group "My workunit".
Matching against just the email address seems to be trivial. Creating a conjunction against the (inverse of the) group membership seems impossible.
Yes, I can do this by doing the obvious explicit cross-checking myself, but if the point of having search functionality directly in Address Book is to optimize performance, wouldn't it make sense for the search facility to be sufficiently complete to be able to do this?
Thanks in advance,
Tony
You could potentially copy all the data from the address book into a Core Data store and use predicates to work with that data. Predicates tend to be very useful when building complex queries.
Predicate Programming Guide
In this case you would have to get all contacts ([[AddressBook sharedAddressBook] people]) and also have a Core Data entity called Contact (or something similar) that would save names, emails, addresses and other properties from the ABPerson object.
Having this you can probably create an NSPredicate to filter with the conditions you want.
Groups reference their members according to recordId. The only way I have found to perform such an operation is here: how to find parent groups of a person. It is not a simple thing like we would like. It seems that Apple is not concerned about group searching which would be extremely useful.