[Gambas-devel] Gambas component queries

[Rob]

On Monday 17 January 2005 23:41, Srikanta Prasanna wrote:
> (Query) Is the init of all the components in a project
> invoked when the project is executed? Or is it invoked
> only when it is necessary (somewhat like 'Just-In-Time') ?
> Similary, when is exit called ?

Init is called when the component is instantiated (most likely 
with "DIM x = NEW AwesomeWidget".)  Exit is called when the 
component is destroyed, either because it passes out of scope 
(at least I think it happens then) or because the program ends.  
In Exit you have to free any memory you've allocated (whether 
using Gambas' built in tools for managing memory, or the usual 
malloc/free stuff, or some other toolkit's equivalent to 
malloc/free), or you'll get the "N allocations not freed" thing 
when gbx exits.

> 2) The GB refernce:
> Is this mandatory for every component?
> If yes, what is the actual use of it in ones component?

I'm not sure what you mean, but I was able to just use 
GB.ReturnInteger, etc. without declaring anything special (I 
just copied the old sdl component over to a new directory and 
moved all the sdl stuff.... with all the recent changes to the 
sdl component you may want to start from a smaller one, like my 
own pcre one.)

> 3) Interpreter Hooks:
> Why are interpreter hooks necessary ?

They're not, or at least I don't think I used any in pcre or 
posix.

> Can we have a component without any hooks to intrepreter ?

Definitely, as far as I know.

> When are these hooks called by the intrepreter ?
> Would the ImageMagick component need any of those ?

I don't know the answers to these questions.

> And finally, what are event-loops ?

An event loop is the main loop of any interactive program (and 
many non-interactive programs).  It is the loop in which the 
program waits for input from a variety of sources (mouse clicks, 
key presses, network activity, etc.), processes them, and then 
goes back to waiting.  Toolkits that can generate events from 
user input generally have their own event loop, and you can only 
use one such toolkit in a given program, which is why the Gtk 
and Qt components in Gambas can't be used at the same time.

Thanks for taking a stab at ImageMagick, and I hope I can provide 
whatever help you need since you will be making my life a lot 
easier ;)

Rob