[Geany-Devel] Let's use Vala

[Matthew Brush]

Hi all,

In the spirit of the previous discussions about using C99 and C++ in 
Geany code with similar subject lines, I'd like to take a 
poll/discussion for allowing the use of Vala for new/re-written Geany 
code. The pros and cons likely will be slightly biased since I would 
obviously like to use Vala in Geany, but here they are anyway:

Pros:
-----

* Power of high-level OOP language using existing GObject backend with 
no C boilerplate required
* Uses same type-system as existing C code
* Automatic memory management
* Clean expressive syntax (foreach, as, properties, signals, async, etc.)
* Exceptions (which uses C/GError-style exceptions in generated C code)
* No extra dependency for release users (generated C code can be shipped)
* Can generate Gobject-Introspection bindings automatically allowing use 
from a bunch of cool languages like Python, JavaScript, etc (and as many 
other languages as support Gobject-Introspection) for plugins.
* Easy to learn for anyone who's used C++, Java, C#, etc.
* Uses all existing dependencies as its runtime library (ex. GLib/GIO).
* Can generate C/H code that is usable from within existing C code, so 
no requirement to completely re-write, can just add on modular code as 
needed.
* Can be tuned to output optimized C code, or call optimized C code 
quite easily
* Can sometimes generate clever and/or optimized code that would be 
tedious to write in C.
* Has Autotools and Waf support already, and using from plain GNU Make 
is trivial.
* Actively developed and supported, and having active mailing list and 
IRC channels. (ex. it's easier to submit a patch to Vala language than 
ISO C).
* AFAIK it generates C89-compliant code :)

Cons:
-----

* A fairly new language (since 2006). It's hard to argue against this, 
but also impossible to move forward without adopting new stuff at some 
point.
* Some dark corners/bugs due to being such a new language (compared to 
C/C++).
* Actively developed so sometimes we probably have to require specific 
valac versions to support certain features (ie. nothing like c89, c99, 
c++98, etc but not unlike supporting newer G* versions).
* As with above, may require to use fairly modern/specific dependency 
versions of the G* C libraries (ex. might not work on RHEL or some other 
LTS distros).
* Extra dependency (valac) for maintainers/developers.
* Using non-GLib-based libraries requires to write boring but trivial 
binding .vapi files (not huge deal for existing Geany code).
* Can sometimes generate heap-heavy or non-optimized code.
* Can sometimes generate C code that causes warnings with common 
compiler warning flags, would require to disable some compiler warnings 
on generated C code to have a completely clean build (ex. use -w on all 
.vala code)
* The documentation isn't as great as an ISO language that existed since 
forever. The official language specification isn't as complete or 
fleshed-out (ex. has TODOs) as an ISO language. There is lots of 
documentation out there, for example on the official Wiki, but it's 
still no substitude for definitive language reference and decades of 
books/literature on the subject.
* More people know C than C++/C#/Java (ie. style of Vala). IMO, this one 
is untrue since people who use C nowadays are either well-versed 
embedded programmers who already know the higher-level stuff, 
C/Gobject/Gtk+ programmers who already know or can easily understand how 
the higher-level stuff works (ex. by looking at generated C code), 
high-level-only programmers who for the most part don't need to care 
about how the underpinnings work and already would know Vala since it's 
basically C#(/Java), or finally, and I believe the least likely; 
complete n00bs who would be much safer writing garbage in any high-level 
language than directly in something like C/C++ anyway.

For more information about Vala, this a good starting point:

     https://wiki.gnome.org/Vala/Documentation

If we can cleanly get more +1's than -1's (in principle, and especially 
from the core developers and active contributors), without wandering off 
into nitty-gritty details, version-specific bugs encountered that 
don't/won't specifically apply to Geany, stuff I have specifically 
accounted for in the pros/cons list, and minutia like we (especially ME) 
always do, then we can move forward with this and hammer-out those 
details later during integration, rather than stifflying the idea here 
in this thread as we (including ME) often do. If one or more of the 
things you like or dislike is already mentioned, there's no point in 
specifically responding to it unless you think it's unclear or 
inaccurate, just give your +1/-1 and see where it goes.

Basically what I'm saying is that if we can keep this discussion on 
track and people show enthusiasm (or at least not strong distain, in 
principle) then I will personally volunteer my time to make it happen. 
If it turns into a zillion message thread about off-topic, or 
nitty-gritty stuff (which should occur later on, in a different thread) 
or hate from people who have never tried the language in earnest but 
still have a strong anti-opinion (especially based on old or presumed 
information, or general hate for the G* toolkit we already use), then I 
probably will just forget it, and probably no one else will move this 
forward.

P.S. Sorry for stupid-sounding discussion rules, it's just an attempt to 
move something useful forward, productively, with consensus, without 
wasting our voluntary time discussing deep details too early-on, and 
based on past similar discussions on this list and knowledge I have 
about some poeple's existing opinions. Please don't take offense or rant 
about the stupid "rules", just believe I'm sincere in that I'm trying to 
organize the discussion more productively than usual (even if failing) :)

Cheers,
Matthew Brush