(This is an in-theory question, to scratch a personal itch, so I am not interested in "IMHO thats-not-advisable" answers, because this is just something to fix some little things, not to be installed on your machine etc... ;-)
I have made a couple of custom Gtk widgets that extend the base widgets such as GtkFileChooser and GtkNotebook.
(not much, but its something, as of yesterday I knew nothing about gtk or c, so this is more of an in-theory question - however if its not possible there is not much point in me learning any more gtk2)
However I would like to use these widgets in all my gtk2 apps.
Is it possible to over ride the default widgets system-wise without rebuilding the gtk2 libs from source?
It looks like gtk-modules would be the way to go, but the documentation seems sparse, unless my googling is missing something.
The purpose of this, is that the GtkNotebook does not support multiple rows of tabs, however it is used in Geany, Anjuta, Bluefish and numerous other gtk2 based editors. I can recompile geany and Anjuta, and bluefish to use my widget instead, but I'd prefer to swap it out across the board.
Normally the right solution to reusing widgets between different applications is to create a dynamic library that adds the widgets.
Remember that it's advisable to create real GObject subclasses with a separate GType. Then it's also trivial to add support for say introspection so your widgets can also be used in language bindings etc.
Related
Cocos2d-x 3.0 alpha was released for some time now. What was improved over cocos2dx-2?
The features list is quite important, but in terms of performance are there new limitations/improvements?
Have you noticed real improvements in performance, development patterns, APIs and support?
I've been using it recently and from what I've noticed the main differences are that everything is namespaced now, so you don't have to deal with the prefixed names that came from the objective c patterns, so cocos2d::Point instead of CCPoint (especially for enums, (Texture2D::PixelFormat::RGBA8888 instead of kCCTexture2DPixelFormat_RGBA8888)).
Also some of the event stuff now has support for c++11 lambdas.
A more complete list of the changes can be found here: http://www.cocos2d-x.org/wiki/Release_Notes_for_Cocos2d-x_v300
but for the most part of using it myself, it's just made to feel more like C++, instead of like objective-c.
I have switched and am finding it pretty stable. The main advantages so far ...
Real buttons, instead of menus
Real-time spritesheets
SpriteBatchNodes are no longer recommended and I did see a drop in draw calls where I not optimized
less objective C patterns.
more modern. namespaced instead of 'CC'. C++11.
more platforms supported
Main disadvantages for me:
EventListener pattern. I can't figure out how to get touch input to affect any objects other than the Node that triggered the event.
We use a lot of text-only buttons for debugging and they are hard to lay out :)
Lack of documentation and example code. For example, I could not find any documentation of how to use the Layout class anywhere.
It is a lot of work porting, but for us we had to decided to risk it since we would end up maintaining an out-of-date code base. It took about 5 person-days to port our game over. The game is now stable and we did not run into a single bug in cocos.
I think its C++11
auto
lambda
And it has no unnecessary use of prefix CC
One of the changes that happened between Cocos2d-x 2.1.5 and 2.2 was the removal of templates for projects in XCode (I do not know if project templates existed in VS, etc).
The new build system creates projects under the Cocos2d-x installation (at least on Mac) and that is where the project files appear to reference them. This makes it very difficult to move the project without hand tweaking. It also makes configuration management more painful, depending on how you set up your system (e.g. a root/tree like svn or a "drop it anywhere" like git).
Also, the Cocos2d-x library is built as that, a library. In previous incarnations, it was placed directly into the project. On one hand, if you don't alter the root library code, this makes good sense. On the other hand, if you occasionally tweak things for a specific project, you have altered all your projects that depend on it. Yin/Yang.
I'm still very positive on Cocos2d-x. I have not upgraded to 3.0 or 2.2 yet. When it matures a little more, I will switch over, regardless the changes. For what I need, I'm pretty sure it will still get the job done (well).
I'm talking about wrappers for third-party libraries. Until recently I was trying to provide a general enough wrapper so I could easily switch libraries if needed. This however proved to be nearly impossible since libraries can vary greatly even in terms of how basic concepts are handled.
So the question came to me why one should use wrappers at all. (In the past I have been encouraged by experienced coders to write wrappers for 3rd-party libs.) I came to the following conclusions; please tell me if they are wrong or if you have anything to add.
If the library isn't widely used in the application (e.g. used by only one or two classes), don't write a wrapper at all, just use it directly. (Especially if it's a portable lib.)
When you do write wrappers don't think you can make one-size-fit-all wrapper. Write something appropriate for the strengths of the lib.
... But in some cases you can still generalize the wrapper enough so that it'll be somewhat easier to switch libraries. (E.g.: most graphics libraries use images and fonts.)
Wrappers are useful for when the library offers more functionality than you need. You can hide the unneeded functionality in the wrapper.
In the case of C libs (if you're using C++), you can also write a wrapper to help you with automatic memory management.
What do you think are the (dis)advantages of using wrappers, and how should they be used properly?
I think you've hit the nail on the head, wrappers just to allow something to potentially be swapped out is a bad idea. The classic example is a database and who has actually ever had to switch from SQL to Oracle (I know people have, but how often and did having a wrapper really help?).
In my experience a wrapper only helps if it is hiding 2+ calls to the 3rd party component or api's into a single call that means something to the calling code (basically a facade pattern) or if it is wrapping the code and adding value / type conversion for the caller (an adapter pattern).
So the wrapper must provide a benefit here and now to the consumer, not a potential future benefit (to the system coder) that may never be needed.
Wrappers are powerfull if you want to test in isolation. For example my development system has no connection to my customers activedirectory that holds usernames and roles. so i have a UserInfoWrapper-Interface with two implementations: one that uses activedirectory and one with fake userdata used for development.
"All problems in computer science can be solved by another level of indirection" by Butler Lampson
There is a cost involved in abstracting third party libraries by creating a wrapper. You need to decide whether the cost is worth it or not. For e.g. it is extremely difficult (or at least involves significant development cost) to create wrapper on UI toolkits or libraries. On the contrary it is relatively easy to create wrappers for third party logging libraries.
Wrapper can also be used to provide domain specific and a simplified API on top of third party libary. Facade pattern could be of help (as Paul Hadfield has mentioned above).
I have a basic problem with knowing which classes to import for a given application, renderer, AS package, mxml component, etc. There seems to be hundreds of classes (both mx and flash) and I'm never sure which one(s) to import... so I just keep adding import statements until the errors go away. Is there a reference somewhere that I don't know about? Or does this just come with experience? Also... does importing a load of classes actually make the file size larger or does Flex only import the classes used nregardless of what I specify? If it only uses what is needed, why wouldn't everyone just do: import mx.*;
I would suggest that if you find yourself bringing in tons of imports, you should ask yourself: Does this class do to much?
It is less of a technical issue, and more of problem of object-oriented design -- maintainability, testability and stability.
I do my best to limit my external dependencies. I try to conform to SOLID principles that tell me that classes should exist for one reason. If a class does too much, it is a "code smell" and an indication that you should split it up.
How much is too much? It is tough to have a specific litmus test or limit... I just ask myself "What does this class do"? If my answer contains an "and" in it, then I consider splitting it up.
I think your problem is a not a real problem if you use any half decent IDE. If you're not using one, you probably should (even if it's not stricly necessary and you can write and compile with notepad and the command line).
If you are using Flex/Flash Builder, it will add the imports automatically (and remove the unneeded ones as well). Also, you can use Ctrl + SPACE to prompt autocomplete, which should add the necessary imports.
Flash Develop also manages this for you (the shortcut was Ctrl + Shift + 1 if I recall correctly, but I haven't used FD for a while).
There are other IDEs out there that I haven't personally used but also have this very basic feature.
If you're using the Flash IDE, well, it really sucks for writting code, so you should probably consider writting your code in some other less brain-dead editor if you plan to do anything more than a couple of lines of code here and there (again, you can write code in the Flash IDE but why not taking advantage of better tools when they're available?).
When you get an error, look at the API Reference for the class, and then either import the whole package or just the class you want. Highlighting the class and hitting F1 should also work (but I never search help this way).
As for file size, see my answer on Is it possible to dynamically create an instance of user-defined Class in Action Script 3?
As Juan pointed out, use FlashDevelop, it is a great (and free) IDE.
If you're using FlashDevelop with the Flex Compiler, you can compile straight from FlashDevelop, and use the refactoring tools they offer to slim down your imports.
Aside from that though, if you're not referencing them, they don't get compiled, so it's not like your compiled swf is any bigger.
How does one study open-source libraries code, particularly standard libraries?
The code base is often vast and hard to navigate. How to find some function or class definition?
Do I search through downloaded source files?
Do I need cvs/svn for that?
Maybe web-search?
Should I just know the structure of the standard library?
Is there any reference on it?
Or do some IDEs have such features? Or some other tools?
How to do it effectively without one?
What are the best practices of doing this in any open-source libraries?
Is there any convention of how are sources manipulated on Linux/Unix systems?
What are the differences for specific programming languages?
Broad presentation of the subject is highly encouraged.
I mark this 'community wiki' so everyone can rephrase and expand my awkward formulations!
Update: Probably didn't express the problem clear enough. What I want to, is to view just the source code of some specific library class or function. And the problem is mostly about work organization and usability - how do I navigate in the huge pile of sources to find the thing, maybe there are specific tools or approaches? It feels like there should've long existed some solution(s) for that.
One thing to note is that standard libraries are sometimes (often?) optimized more than is good for most production code.
Because they are widely used, they have to perform well over a wide variety of conditions, and may be full of clever tricks and special logic for corner cases.
Maybe they are not the best thing to study as a beginner.
Just a thought.
Well, I think that it's insane to just site down and read a library's code. My approach is to search whenever I come across the need to implement something by myself and then study the way that it's implemented in those libraries.
And there's also allot of projects/libraries with excellent documentation, which I find more important to read than the code. In Unix based systems you often find valuable information in the man pages.
Wow, that's a big question.
The short answer: it depends.
The long answer:
Some libraries provide documentation while others don't. Standard libraries are usually pretty well documented, whether your chosen implementation of the library includes documentation or not. For instance you may have found an implementation of the c standard library without documentation but the c standard has been around long enough that there are hundreds of good reference books available. Documentation with hyperlinks is a very useful way to learn a new API. In any case the first place I would look is the library's main website
For less well known libraries lacking documentation I find two different approaches very helpful.
First is a doc generator. Nearly every language I know of has one. It basically parses an source tree and creates documentation (usually as html or xml) which can be used to learn a library. Some use specially formatted comments in the code to create more complete documentation. JavaDoc is one good example of this. Doc generators for many other languages borrow from JavaDoc.
Second an IDE with a class browser. These act as a sort of on the fly documentation. Some display just the library's interface. Other's include description comments from the library's source.
Both of these will require access to the libraries source (which will come in handy if you intend actually use a library).
Many of these tools and techniques work equally well for closed/proprietary libraries.
The standard Java libraries' source code is available. For a beginning Java programmer these can be a great read. Especially the Collections framework is a good place to start. Take for instance the implementation of ArrayList and learn how you can implement a resizeable array in Java. Most of the source has even useful comments.
The best parts to read are probably whose purpose you can understand immediately. Start with the easy pieces and try to follow all the steps that are hidden behind that single call you make from your own code.
Something I do from time to time :
apt-get source foo
Then new C++ project (or whatever) in Eclipse and import.
=> Wow ! Browsable ! (use F3)
We have a website that uses #include file command to roll info into some web pages. The authors can access the text files to update things like the occasional class or contact information for the department.
My question is this, I don't see anyone using this method and wonder if it is a good idea to keep using it. If not, what method should I transition to instead?
I don't think there is anything wrong with it, and I've done some similar things with PHP. If the people that make the changes are comfortable with how they do it and they can do what they need to, I think you should stick with it. There could be some retraining involved and/or a fair amount of work involved for changing the system.
If you are using ASP.NET then you could bundle that code into a nice little UserControl that will display all of the important information.
Other platforms should allow you to bundle the logic into a class object, and display it using that.
It really depends on the platform that you are using to deploy the application in. The include file could be your best solution if you are deploying in a more limited platform.