Re: [Vala] Vala - generates code at runtime

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 ( 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>

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