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Software Engineering of GUI Programming?
cucucu asks: "After ten years of programming for the network, I started programming a GUI Desktop application. My problem is most GUI tutorials out there are nothing more than a taxonomy of buttons, dialogs, and check-boxes. So as I checked GUI toolkits, I found that I can easily learn all the widgets, layouts, callbacks, and the like, and start coding a GUI application. However, very soon I found myself repeating code all over the place. Is there a good guide (online or off) for the Software Engineering aspects of GUI programming, so that I can learn how to reuse code, and build my class hierarchies over the one provided by the toolkit?"
I do Java Swing GUIs and I tend to agree with you. The eclipse visual editor plugin makes GUI creation very easy, but it has it's limits. Almost every time I have used it, I have hit some point at which I wanted to do something that the visual editor did not understand. When I hit that point, I have to get in and code it by hand. Since I learned how to do it from code when I started, this is not too much of a problem. So it does help to know what the code means.
Most people don't seem to think about refactoring their GUIs; already there's one post here telling you not to code your GUIs but use the pathetic drawing tools to create them, even though GUI builders are evil, and one of the very reasons they are evil is they preclude even the simplest refactorings. The bulk of programmers seem to be happy about that.
My experience is that there really isn't anything special about GUI refactoring vs. any other kind of refactoring, at least in the languages I use. That may be a factor; dynamic languages like Python or Ruby seem to be a lot easier to implement "Don't Repeat Yourself" in. You may find you'd be better off switching to one of them, especially if you're trying to work in Java, with seems to elevate repeating yourself to a moral imperative.
But beyond that, I don't really see what's special about GUIs.
The other thing is that when you are first learning an environment, you need to cut yourself some slack. No matter what you do, your first few cuts will suck as you are getting your bearings. I'm all about refactoring and testing, but when I recently picked up Django, I didn't worry about either at all in the first week. Now I have to go back and re-examine everything I did and get the testing going for it, but I don't see any practical way to avoid it; testing my initial garbage would just increase the investment into code that I'm basically throwing away anyhow. (As I have a lot of web experience, that's probably faster than usual; any other framework type would probably take me longer.) You may find that you have built "one to throw away"; consider actually doing so.
Alright, I'm a little busy right now so I won't go into as much detail as I'd like, but here are the basics as far as I understand them.
:) Hopefully other people will have more details to give you.
1) Design patterns still apply. More than ever, actually. If you've not read the GoF, it features a pretty advanced example centered on the design of a rich text editor. You will probably want to dive deeply into the workings of the Model-View-Controller pattern and the related design constructs. The MVC pattern is not the be all and end all of GUI design, and there are many cases where the articulation between View and Controller
2) You may not now it yet, but you want loose coupling. Loose coupling means that, essentially, when a widget's state change, it will report on that change, and some interested party will be notified about it, and neither will have to know anything about the other. Many toolkit nowadays come with good signal and slot mechanisms to implement loose coupling. Understand them, and use them. If you find the sender of a signal and the receiving slot need to know about each other, you may want to go back to the drawing board as suggested in point #1 above; it is usually not necessary.
Conceiving GUIs is not all about the underlying software architecture, though; a good chunk of the work of making great interfaces is in the designing of the GUIs themselves (which is why you want loose coupling -- you WILL have to be flexible against changes as you experiment). I will let others fill you in about that. Quickly: read usability guidelines and get a feel for why they suggest what they suggest. Align your widgets! NetBeans is good for this, IIRC. Use GUI designer tools, experiment more.
That's all I can think of off the top of my head, but there's already a lot for you to chew in there.
All in all, it boils down to the usual rules of engineering: the second rule is to know what works, and the first rule is to know why it works.
-- B.
This sig does in fact not have the property it claims not to have.
Some resources:
Apple's User Interface Guidelines; adapted from the NeXT/OpenStep Interface Guidelines (PDF).
There's also the Classic "Macintosh Human Interface Guidelines" for System 1 through OS 9 (have to hunt it down yourself), GNOME's HIG,KDE's, and Tog's.
Without reading through them all, I can't point out where they address BPs for reuse, management, etc., but I know it is touched on somewhat (although from a NeXT slant) in Apple and NeXT's guidelines.
That's probably overstating it by a fair margin. ;)
Many parts of C# are awesome, and work very nicely:
- GDI+ is extremely easy to use and predictable.
- I like the way they've organized System.IO and System.Collections.
- The Win.Forms control set is very, very well-done.
- XML web services and Regex are also quite passable.
- Reflection is nice, even though I don't often have a chance to use it.
- ADO.NET's simple classes (Connection, Command, DataReader) are very straightforward, and I use them all the time in my database stuff.
- The Setup and Deployment projects are absurdly easy to use. I love it!
Other parts are so-so. They work, but they're not really intuitive, and I frequently find myself referring back to previous projects in order to remember how it works. Examples:- System.Security.Cryptography, for instance, has a whole lot of junk. When all I want is to generate a set of RSA keys and encrypt something, I still have to refer back to prior code samples.
- Their weird proliferation of Stream types, with all of those weird Formatters, is very confusing. I don't like it.
- Globalization has a lot of byzantine stuff in it that I find very confusing.
- DataSet and DataAdapter are overly complex.
- Events and Delegates are a little too crufty. I don't like the syntax (event += event handler? are you kidding?), and I don't like the fact that if the event doesn't have at least one subscriber, it's Null, and will thrown an exception if you raise it. That's stupid.
Then there are the parts that completely suck:- Resource files? Totally botched! I still have no idea how to create a stupid resource file containing some bitmaps, and have it bundled into the application.
- DataBinding. It is practically impossible to glue a textbox to a string, and have bidirectional updating. I don't understand how MS could have so badly wrecked this stuff.
- The credentialing (Code Access Security, User Security, etc.) is so hopelessly complicated that I won't touch it with a ten-foot pole.
- ASP.NET is very, very, very clunky. None of the controls work right, or in a predictable fashion. They don't even work anything like their Win.Forms counterparts! I can design very beautiful Win.Forms GUIs, but my ASP.NET projects always come out looking like third-grade HTML projects. Terrible!!
I had big hopes for C# 2.0 - but it seems to be a little less stable and predictable. Generics, for instance, are a much-needed feature - but Microsoft didn't bother to implement it for ArrayList, the data structure that I use most often. And the new ADO.NET stuff is hopelessly complicated and useless.So despite its flaws, C# is still the drop-dead easiest API I've ever used. I've written several dozen projects in it, and I will continue to use it until something cleaner comes along. (I'm not holding my breath on that one!)
- David Stein
Computer over. Virus = very yes.
Generics, for instance, are a much-needed feature - but Microsoft didn't bother to implement it for ArrayList, the data structure that I use most often.
.NET Framework including ASP.NET and who all knows what crap you don't need, it probably would have replaced C++ for many applications already. Something like perl2exe for C# is what I want. Just bundle the runtime and the JIT and your code up in one nice tidy ready-to-run executable. That would do wonders for the adoption of C#.
ArrayList is still its original, non-generic self for compatibility reasons, but the new List<> class is its excellent replacement in the System.Collections.Generic namespace, along with the generic Hashtable replacement, Dictionary<,>. Don't know why they felt the need to change the names, although ArrayList->List was an improvement...
Other than that, I agree. I'd just put events and delegates farther down under the "completely suck" section. They were really botched and it makes certain things a lot harder than they should be. Also, I'd mention the single greatest thing about C#, IMHO its saving grace: C/C++ interop. The design of the interop with legacy code is nothing short of brilliant. It's five minutes work to wrap and call a random C function, no matter if it takes pointers to weird structs or even a callback! And because of that, C# actually stands a chance of displacing C++ as the language of choice for Windows applications.
If only Microsoft had fixed it to allow distributing C# applications with their own stripped-down runtime included, instead of requiring administrative install of the full 20+ MB
Firebug. It will make your jaw hit the floor.
I didn't see this mentioned in other posts, but I think it's very important:
Decouple your GUI from the code that does the work.
I really don't have a lot of experience with GUI programming, but I do know that there are many different toolkits on different platforms, each comes with its own guidelines, and these guidelines are subject to change over time. At some point down the line, you or someone else is going to want to change the GUI, while keeping the functionality. Moreover, you or someone else may want to drive the application from a script, or from the command line (some platforms may even require one or the other for applications that are considered good citizens). In other words, your application _is_ going to have more than one interface - make sure that is easy to accomplish.
Please correct me if I got my facts wrong.