What are the disadvantages of the Tk module compared to other solutions to create a GUI in Perl?
I toured the various gui modules for Perl recently, and here is my summary (disclaimer: ultimately I found that none of the existing modules met my needs so I started writing my own gui toolkit).
Tk - Decent to work with and the interface is very perlish. The gui itself is a bit dated looking, and doesnt take advantage of any of the operating system's native widgets (like filepickers). On most systems it will require a C compiler to install.
Wx - Difficult to work with, un-perlish interface. Large programs almost require a gui builder to keep track of everything. Support for os level widgets is mixed. Nicer looking than Tk IMO. Compilation is involved, requires installing several libraries, can be difficult to get running on windows. The assembly of programs is very procedural, and does not map cleanly to what the program will actually look like.
Qt - last I looked this module was more or less abandoned and only supports Qt3. I didn't try to install it, but i imagine it needs a compiler.
Prima - Similar to Tk it has a dated appearance. Requires a compiler.
W32::GUI - I ruled this out early since it is not cross platform.
XUL::Node / POE::XUL::Node - rather heavy dependency tree that includes C code. Seems unmaintained and I had mixed experiences getting it to install. Windows was a no go, OSX was a no go, it had limited functionality on OpenSUSE. It also only supports a subset of the XUL language.
I found that none of the existing gui toolkits made it easy enough to distribute your application to end users. It is ok to expect programmers to jump through the hoops of resolving library dependencies and compiling code, but end users aren't going to do that. So the first requirement I had was to be pure Perl.
Secondly, nearly all of the existing gui toolkits force you to work in a very procedural manner: Create a container. Create a packer for the container. Create an object. Set properties on that object. Add the object to the packer. Run the packer to fill the container object. Repeat.
Instead, I find that nested design (like HTML) is easier to follow for two reasons. First off, since objects are nested, there is no need to name everything (label_456, label_457...). Secondly, the structure of the program mirrors the structure of what is displayed.
So I started work on XUL::Gui, and its been coming along rather well. It is pure Perl, and only depends on core modules for ease of installation. It has one external requirement, which is that a recent (3+) copy of Firefox is installed. It uses the familiar design pattern of web development with nested tags styled with CSS. It is certainly at a level where you could write fully featured single window applications with it.
Hopefully this helps you to figure out which toolkit is best for your project.
Tk has not been developed in a very long time. ActiveState now recommends development with their Tkx toolkit, which provides a thin layer over TclTk. It means that themed widgets are possible. But, TclTk is still quite primitive compared with many other GUI toolkits.
I haven't tried XUL:Gui but it seems the way to go.
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I am trying to create my own programming language but I am already thinking ahead a little.
Of course when I can compile a little program I won't have a Standart Library at that time,
and you'd have to create one yourself. Now take for example I'd like to add some functionality to print a string to the screen, I am pretty sure I'd have to do a few System Calls to the operating system to get this displayed.
So to the point: What would be the best way to interact with the Operating System?
Possibilities I came up with myself:
- Generate Object Files and link those to the (for example) C Standart Library
- Writing the files with embedded assembly language containing System Calls
I have a feeling there are better possibilities!
I hope you can help me,
Christian
EDIT: It's a compiled language I am creating!
You have basically two options, like you say yourself. You can link your standard library with the standard C library, so that the I/O functions in your standard library can use C functions. Alternatively you can make system calls to the operating system directly.
The second approach seems like it's going to be more work: The system calls will be different on each operating system, so you'll have to put a lot of work into porting your system. The system calls may not be well documented, causing many frustrations.
You could start by linking your standard library to the C standard library and worry about other aspects of your language for the moment. Later you can look into replacing the C functions you use with syscalls.
Stdin and stdout are pretty much the minimum - if you are using a Unix environment you can then gain access to they keyboard, command line and also pipe text in and out to files.
If you are writing a new language - then StdError may also be worth considering too!
I am curious to know if there is any kind of programming library/framework for the C language for cross-platform programming of course. I mean there are already frameworks like Wxwidgets, Boost, Qt, U++ and etc for C++ available but I have not yet found any for C .
Updated Info:
We are trying to build an underlying Framework/library to be used in our project. We are going to eliminate the dotnet and instead provide a counterpart for those libraries which is fast and less demanding.
We will be working on a server/client based project, and thus the underlying services must be fast and also portable. GUI is not our priority now, but libraries providing threading capabilities is of importance to us.
And for the ANSI part, I think we are fine with that at the moment unless something changes that in the future.
if you write plain ANSI C, it should work on every POSIX system.
The most successful example of cross platform C library is standard C library itself (IMHO).
If you're looking for GUI toolkit GTK is the answer,
if you're looking for terminal UI, ncurses is pretty portable.
If you're looking for general use libraries, as long as they're written in ANSI C, should work almost everywhere, as long as it doesn't use system level APIs.
Can you just tell us, what kind of library/framework you are looking for ?
GTK+ is long established and actively maintained cross-platform C-only (or primarily) toolkit. You'll find not only on-line documentation but also books written about it. It is the framework backing up the GNOME project.
GTK+ is meant to build applications with UI, first of all. However, even if you don't need UI you'll find that some GTK+ components, namely GLib, provide general multiplatform support comparable with Qt. Actually, I needed a framework without UI at first and chose GLib over APR because I was able to find documentation and tutorials easier.
GTK+ was initially developed on UN*X an X-Windows which remains the platform where you can get it running the most easily. I wouldn't say that it is more difficult on Windows; it is just that you have more compiling environment options. I started with prepared GTK+ packages and MinGW but ended up integrating GTK+ with MSVC.
GTK+ exists for a long time and some people may find it old-school. On the other hand, it shows that it has proven to be stable and useful. There are also bindings for C++ and C#.
As with every big framework, the more you need from it the longer you will have to learn. But the other way round it works too; the more you learn the more you'll be able to do with it. Consistent coding style helps getting used to it.
--- Ferda
we start to write plug in for eclipse to work with some java frame work like hadoop (we want to edit hadoop eclipse plug in and merge it with other. our plug in must work in Linux operating system. Generally writing plug in for eclipse depend on operating system or not? if depend what benefits to write it for Linux?
Well, the previous answer is correct... in most cases. You should specifically check all the interfaces with the operating system.
SWT is a Java wrapper over native OS widgets. It behaves almost the same on all OSs, but not exactly. There are subtleties. For example, events that might be fired a bit differently, drawing of widgets, etc. My experience shows that you have to check on all OSs to be sure that it works as it should, especially if you are doing more complex UI rendering. In many cases I had to do some fine tuning to get it right. It is not a great deal of effort, but it should be considered.
Another issue is working with the file system. For example, make sure you are composing files paths correctly. It is always a good idea to test that part as well.
Eclipse plugins are platform independent (you are writing them in Java), unless your plugin requires some low-level calls to the operating system (i.e. JNI) or to invoke some tool found only in the Linux OS.
The only part of Eclipse tied - in part - to the OS is the SWT toolkit, since it's optimized for the graphic environment you are running it, but if Eclipse can run in the OS you are interested in, you should not be bothered by this.
I've been around Visual Basic for years in high school, and I've grown up with the IDE supplied by Microsoft. It'd wonderful, but the educational and "working-model" editions of VB available to me through school don't allow me to redistribute software, as part of the EULA with Microsoft.
I instead find myself working in perl to design programs for friends and family, and it works fairly well, but I don't have a firm grasp on building user interfaces yet. I understand I could design user-interfaces with tcl/tk for perl, but the notion of coding all of that by hand is a bit daunting to me. That brings me to my question.
Do you have any suggestions for a tool I could use that would allow me to build GUIs for my perl programs?
Thanks in advance!
In addition to what tsee suggested, you can have a look at :
Perl/Qt (using Qtdesigner) and Perl::GladeXML (using Glade)
With Glade and Qtdesigner, you can generate a XML file that will describe your user interface and it will be a matter of hooking your perl code to widget's events.
I don't think you will find something as simple and well integrated for Perl as the Visual Basic GUI builder. A couple of pointers:
wxGlade can be used to design GUIs for the Wx GUI toolkit (for Perl, not only Python).
For Win32::GUI, you can use the GUI Loft to achieve something similar.
I think there's a bunch of other GUI builders including at least one for Tk, but I don't remember the name.
Either way, I believe you will have to accept that you have to do more coding vs. designing when compared to VB. The upside is that if you use Tk or Wx, your programs may well be portable to all major operating systems.
For a Perl-specific development environment, you might want to check out Padre, which is itself written in Perl using Wx. It's under active development, so eventually, somebody will probably integrate a GUI builder, too.
Frankly, having thought about GUIs for years and never getting round to them, I've found the best way to distribute GUI apps with perl is to use Catalyst, its built in server and for windows users, distributing it with Strawberry Perl (the professional edition comes with Catalyst included). For Linux or Mac users a local::lib installation to pull in the required cpan modules. Optionally bundle in a copy of portable firefox if you want not to have the usual web development pain caused by internet explorer.
tl;dr; Sidestep the whole issue by going for web development with a framework that comes with its own standalone server.
Is there a general procedure for programming extensibility capability into your code?
I am wondering what the general procedure is for adding extension-type capability to a system you are writing so that functionality can be extended through some kind of plugin API rather than having to modify the core code of a system.
Do such things tend to be dependent on the language the system was written in, or is there a general method for allowing for this?
I've used event-based APIs for plugins in the past. You can insert hooks for plugins by dispatching events and providing access to the application state.
For example, if you were writing a blogging application, you might want to raise an event just before a new post is saved to the database, and provide the post HTML to the plugin to alter as needed.
This is generally something that you'll have to expose yourself, so yes, it will be dependent on the language your system is written in (though often it's possible to write wrappers for other languages as well).
If, for example, you had a program written in C, for Windows, plugins would be written for your program as DLLs. At runtime, you would manually load these DLLs, and expose some interface to them. For example, the DLLs might expose a gimme_the_interface() function which could accept a structure filled with function pointers. These function pointers would allow the DLL to make calls, register callbacks, etc.
If you were in C++, you would use the DLL system, except you would probably pass an object pointer instead of a struct, and the object would implement an interface which provided functionality (accomplishing the same thing as the struct, but less ugly). For Java, you would load class files on-demand instead of DLLs, but the basic idea would be the same.
In all cases, you'll need to define a standard interface between your code and the plugins, so that you can initialize the plugins, and so the plugins can interact with you.
P.S. If you'd like to see a good example of a C++ plugin system, check out the foobar2000 SDK. I haven't used it in quite a while, but it used to be really well done. I assume it still is.
I'm tempted to point you to the Design Patterns book for this generic question :p
Seriously, I think the answer is no. You can't write extensible code by default, it will be both hard to write/extend and awfully inefficient (Mozilla started with the idea of being very extensible, used XPCOM everywhere, and now they realized it was a mistake and started to remove it where it doesn't make sense).
what makes sense to do is to identify the pieces of your system that can be meaningfully extended and support a proper API for these cases (e.g. language support plug-ins in an editor). You'd use the relevant patterns, but the specific implementation depends on your platform/language choice.
IMO, it also helps to use a dynamic language - makes it possible to tweak the core code at run time (when absolutely necessary). I appreciated that Mozilla's extensibility works that way when writing Firefox extensions.
I think there are two aspects to your question:
The design of the system to be extendable (the design patterns, inversion of control and other architectural aspects) (http://www.martinfowler.com/articles/injection.html). And, at least to me, yes these patterns/techniques are platform/language independent and can be seen as a "general procedure".
Now, their implementation is language and platform dependend (for example in C/C++ you have the dynamic library stuff, etc.)
Several 'frameworks' have been developed to give you a programming environment that provides you pluggability/extensibility but as some other people mention, don't get too crazy making everything pluggable.
In the Java world a good specification to look is OSGi (http://en.wikipedia.org/wiki/OSGi) with several implementations the best one IMHO being Equinox (http://www.eclipse.org/equinox/)
Find out what minimum requrements you want to put on a plugin writer. Then make one or more Interfaces that the writer must implement for your code to know when and where to execute the code.
Make an API the writer can use to access some of the functionality in your code.
You could also make a base class the writer must inherit. This will make wiring up the API easier. Then use some kind of reflection to scan a directory, and load the classes you find that matches your requirements.
Some people also make a scripting language for their system, or implements an interpreter for a subset of an existing language. This is also a possible route to go.
Bottom line is: When you get the code to load, only your imagination should be able to stop you.
Good luck.
If you are using a compiled language such as C or C++, it may be a good idea to look at plugin support via scripting languages. Both Python and Lua are excellent languages that are used to script a large number of applications (Civ4 and blender use Python, Supreme Commander uses Lua, etc).
If you are using C++, check out the boost python library. Otherwise, python ships with headers that can be used in C, and does a fairly good job documenting the C/python API. The documentation seemed less complete for Lua, but I may not have been looking hard enough. Either way, you can offer a fairly solid scripting platform without a terrible amount of work. It still isn't trivial, but it provides you with a very good base to work from.