gtkDcoding Blog Post for 2019-03-29 - Grid

[Mike Wey]

On 02-04-2019 17:48, Ron Tarrant wrote:
> On Tuesday, 2 April 2019 at 14:13:09 UTC, number wrote:
> 
>> Can somebody explain why getRgba() (apparently inherited from 
>> ColorChooser) does take an out parameter instead of returning an 
>> Gdk.RGBA?
> 
> My understanding is this:
> 
> Returning an object (as opposed to a single value) means returning a 
> pointer rather than the entire object. And the object will cease to 
> exist once the function returns because the scope no longer exists. So, 
> it follows that an out variable passed in will preserve the object 
> itself once program control returns to the caller.
> 

While that would be true for things that live on the stack, this is not 
the case for RGBA. The C version of getRgba uses the "out" parameter so 
you can pass in a existing GdkRgba, even tough that would make it more 
like ref.
This doesn't make sense for the d binding since you will always get a 
new RGBA passed through the out parameter.

-- 
Mike Wey