Re: [Vala] Vala - generates code at runtime

[jideel <jideel free fr>]

Thanks for your response.
You're probably right, perhaps it's not the right tool.
It was quite seductive to be able to code as easily as with C#/Java while having C performance/size.
The project is about a kind of distributed UUID generator, available through different interfaces (socket, 
soap, rest...) , while being manageable through a web interface, users can define their own types/classes 
on-the-fly and link generated UUIDs to their objects so later they can pick up an UUID from, say, a database 
and find what kind of object it's related to, when it was created and so on. It can provide some tracability 
to a normally "dumb" identifier.
As it has to be reliable/scalable/... it's probably a java-like job.
I've investigated Java/C# previously for such a task and it's true it fits well, but i had a good feeling 
about Vala, so i thought "why not give it a try ?" :)
Vala is perhaps, at least for now, more desktop-oriented.
Anyway, it doesn't seems that the gmodule-2.0.vapi wraps any unload functionality, while GModule provides a 
GModuleUnload function. Is it not implemented or am i missing something (again) ?



Le 9 févr. 2010 à 21:57, Jan Hudec a écrit :

> On Tue, Feb 09, 2010 at 15:36:56 +0100, jideel wrote:
> > I'm wondering what would be the "right" way to generates code/classes at runtime, and reload it into the 
> > running program.
>
> Well, is Vala the right tool than? It's a completely static language which
> needs to be compiled with C compiler and that linked and the C compiler and
> linker are a pretty big beast. Something more dynamic would handle the job
> easily. Either fully dynamic like python (or perl or ruby or lua or
> javascript (using libseed)), that have no compilation at all, or partially
> dynamic like CLR (Mono/.NET) or Java, which both carry their bytecode
> compiler in the runtime. You can still use vala for the static part and
> export necessary API to the dynamic part.
>
> > I thought to use the modules/plugin approach (http://live.gnome.org/Vala/TypeModules) the following way :
> > - generate code than can be reloaded (plugin code, [ModuleInit]) using some kind of StringBuilder
> > - flush it to a file
>
> I would not compose to StringBuilder (which is just string and will
> reallocate all the time as you extend it), but write to a file directly. It
> would be more efficient and you really get similar functionality.
>
> > - compile this file either by forking a valac compiler or perhaps using directly libvala (possible ?)
>
> Both are possible. Forking is probably easier, since while most of vala
> compiler does live in libvala, the driver is not too trivial. Might depend on
> the conditions. I found the code reasonably easy to follow, so just take
> a look.
>
> > - reload the resulting plugin binary into the app
>
> It should work. You need to unload the old version, so you need to shut it
> down and than reload. Mostly applies to CLR and Java too; fully dynamic
> languages should be able to upgrade.
>
> > There's probably a better way to accomplish this kind of task.
> >
> > Any idea / suggestion ?
>
> It really depends on *why* you want to do it.
>
> -- 
>                                                Jan 'Bulb' Hudec <bulb ucw cz>