• Ron Tarrant (22/22) Apr 17 2019 I've come across this a few times in the wrapper code for GtkD
• Adam D. Ruppe (5/8) Apr 17 2019 Those aren't the same thing! One is Adjustment, the D wrapper
• Adam D. Ruppe (7/7) Apr 17 2019 btw if you haven't seen my version of the gtk-d docs, check it
• Ron Tarrant (3/12) Apr 17 2019 Ah! Thanks for clearing that up, Adam. I shall go blush now for

Ron Tarrant <rontarrant gmail.com> writes:

I've come across this a few times in the wrapper code for GtkD 
where one of the constructors for an object takes an argument of 
the same type the constructor produces.

For instance, one of the Adjustment constructors looks like this:

	public this(GtkAdjustment* gtkAdjustment, bool ownedRef = false)
	{
		this.gtkAdjustment = gtkAdjustment;
		super(cast(GObject*)gtkAdjustment, ownedRef);
	}

I have a vague memory of finding out how to use this type of 
constructor from a while back, but I can't remember how. And if I 
did find out, I neglected to take notes, apparently (shame on me) 
but I may also have dreamed it.

And I can't find a cogent example.

At first glance, this form of constructor seems impossible to 
use. I mean, how can I instantiate an object passing the object 
(which doesn't exist) as an argument?

Or is this not actually a constructor?

Or maybe there's some magic going on here that I'd understand if 
I knew D better?

I keep running across this, so I'm hoping someone can give me a 
leg up.

Adam D. Ruppe <destructionator gmail.com> writes:

On Wednesday, 17 April 2019 at 14:49:33 UTC, Ron Tarrant wrote:
 For instance, one of the Adjustment constructors looks like 
 this:

 	public this(GtkAdjustment* gtkAdjustment, bool ownedRef


Those aren't the same thing! One is Adjustment, the D wrapper 
class, and the other is GtkAdjustment*, the C structure pointer.

This constructor is for cases when you have an existing object 
made via the C api and you want the D wrapper to adopt it.

Adam D. Ruppe <destructionator gmail.com> writes:

btw if you haven't seen my version of the gtk-d docs, check it 
out:

http://gtk-d.dpldocs.info/gtk.Adjustment.Adjustment.html

It does various cross-referencing the official versions don't, 
among other things. You can see the GtkAdjustment there is not 
linked, because it is the C version, whereas references to 
gtk.Adjustment are links to the D classes.

Ron Tarrant <rontarrant gmail.com> writes:

On Wednesday, 17 April 2019 at 15:05:22 UTC, Adam D. Ruppe wrote:
 On Wednesday, 17 April 2019 at 14:49:33 UTC, Ron Tarrant wrote:
 For instance, one of the Adjustment constructors looks like 
 this:

 	public this(GtkAdjustment* gtkAdjustment, bool ownedRef


 Those aren't the same thing! One is Adjustment, the D wrapper 
 class, and the other is GtkAdjustment*, the C structure pointer.

 This constructor is for cases when you have an existing object 
 made via the C api and you want the D wrapper to adopt it.

Ah! Thanks for clearing that up, Adam. I shall go blush now for 
not reading more closely.