On Friday, 11 May 2012 at 22:28:55 UTC, Jacob Carlborg wrote:
On 2012-05-06 21:55, Mehrdad wrote:
Is this possible in D2?
i.e. I'm wondering if there is a way to do the object
construction yourself, which would allow you to call the
object's
"constructor" (initializer) manually, and just return a pointer
to the new object.
Something along the lines of:
class Window
{
static Window opConstruct(void* ptr)
{
// Assume ptr is already correctly sized and filled
Window result = cast(Window)ptr;
result.__ctor();
return return result;
}
}
It seems like overloading new() *almost* does this, but not
quite: It only lets you allocate the memory, not call the
constructor yourself.
This would be useful, because some objects can have external
constructors (notably when interfacing with C/C++, such as when
using CreateWindow() in Windows), and you *cannot* call these
constructors inside the object's "constructor" (initializer)
due
to re-entrancy issues.
Don't know if it helps but, have a look the DWT sources:
https://github.com/d-widget-toolkit/org.eclipse.swt.win32.win32.x86/tree/master/src/org/eclipse/swt
should probably be in the internal folder, widgets/Widget or
widgets/Shell.
Thanks for the link.
It seems like it's on Control.d...
Yup, they do what C# does with the constructor: they put make a
*separate* function, createHandle(), used to create the control.
And they simply *don't* tie the destructor to DestroyWindow();
instead, they just assume the user will call dispose().
So in other words, they just ignored the entire problem with the
lifetimes, and hoped ("required"?) that the user will call
dispose().
Not something I'd want to do, since (even according to .NET's
philosophy) a handle leak must NEVER occur, as long as the
program has control, even if the user doesn't dispose the object.
The closing of the handle can of course be nondeterministic due
to the GC, but it must be eventually cleaned up when the object
is GC'd.
Any ideas if this would be easy/hard to add to DMD/Phobos?
