Re: [Vala] Interfacing various languages

[pancake <pancake youterm com>]

i think that before accepting patches we need a plan. We have to decide
if we want a subset of Vala, or just to define an interoperability API to
call other languages like C++, Java or ObjC.

if the plan is to use it just with bindings one can use Valabind, which can
create JNA/JNI or C++ bindings from Vala code (still wip) and then just use
that api from Java or C++ code.

But I would prefer to be able to call OBJC/C++ code from Vala. The 
emscripten
solution to that problem is quite elegant, so maybe we can use it as a way
to create formatted strings at compile time for the generated code. For 
example:

using Interop;

void main() {
    string msg = "Hello World";
    Interop.cpp ("std::cout << ", msg, ";");
}

This will create the following code:

std::cout << msg; which is valid C++ code, and therefor we can compile the
generated c code from Vala using G++.

The same can be used for ObjC, but it would be great if we could use a more
idiomatic way for that. The vala-objc fork used to completely replace glib
with objc apis, so a 'class lala' would be compiled into a .m file that can
be compiled with an objc compiler.

So we can have different approaches to this problem:

* Transpile to other target languages (java, objc,..)
* Permit a more complete code generation to call C, C++ and ObjC apis
* Generate bindings for other languags (already done with valabind)
* Create wrapper code to wrap C++/ObjC classes into glib ones.
* Create a sub-language of Vala that can be used for portable code
* Make different profile targets to handle different runtimes (glib, 
posix,.. that's how this was done in the past)
* Extend the compiler with a plugin API to handle different codegen 
backends.

What do you think? After some disucssion I would suggest to open a pad
and continue the design discusison there.

--pancake


On 11/08/2014 01:15 PM, Luca Bruno wrote:
> Talking in general here. I would accept patches in the vala compiler 
> for multiple targets only if they are generic enough.
> It's a long iteration, but I don't want after N months of inactivity 
> of a target to revert it because nobody maintain it.
>
> For this reason, I accept small patches, step by step, to generalize 
> the current vala compiler and codegen to allow more pluggability.
> I'm not willing to merge big stuff at once especially if those are 
> invasive and do not permit a generic reuse of the compiler.
>
> You have my support for merging the stuff in Vala, but really it must 
> be generic so that maintainability is not a problem in the future.
>
> On Sat, Nov 8, 2014 at 1:10 PM, Marek Gibek <gibekm gmail com 
> <mailto:gibekm gmail com>> wrote:
>
>     Hi!
>
>     I'm thinking of doing the same thing - use Vala to target Android,
>     iOS, Windows Phone but also Windows and Linux at the same time!
>
>     But I do not think that compiling to Java on Android or to objective c
>     on iOS is required. We can simply create a native library from
>     application code with standard vala->c->bin compilation process. And
>     then write specific wrapper/library loader in Java/objective-c only if
>     it's not possible to do it in C.
>
>     That would require to port glib and gobject to every platform. Thanks
>     for info about posixvala - this can be useful.
>
>     I would go even further and I want to prepare the same API wrapper for
>     all platforms. That would allow me to write code once and recompile
>     for every platform. Abstraction of UI library will be more time
>     consuming. Probably creating new one in OpenGL is an option here. As a
>     bonus you can run the same app from the same code everywhere.
>
>     I updated Vala plugin for MonoDevelop that runs fine on both
>     Windows and Linux:
>     https://github.com/marek-g/ValaBinding
>
>     Now I'm working on more complex solution based on IntelliJ - the best
>     IDE I am aware of. But it is not open-source for now.
>
>     Actually it requires great amount of work. My dream is to find a
>     sponsor or company that could hire me full-time and give me a small
>     team to lead to create complete product. If someone is interested,
>     this is my linked-in profile:
>
>     http://pl.linkedin.com/in/marekgibek
>
>     I think there is strong need on the market for such product!
>
>     /Marek
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>
>
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