A template construct like using()

[H. S. Teoh]

On Tue, Apr 26, 2022 at 09:33:43PM +0000, Chris Katko via Digitalmars-d-learn wrote:
[...]
> I'm looking for a construct that mimics using(var)/with(var)
> 
> ````D
> bitmap* b;
> 
> draw_with(b)
>   {
>   draw_pixel(red, 16, 16); //draw red pixel to bitmap b (b is implied above)
>   }
> ````
> 
> But the code ends up being:
> ````D
> bitmap* b;
> 
> set_target_bitmap(b); //entry code
> draw_pixel(red, 16, 16); // body
> set_target_bitmap(original_target); // exit code
> ````
> 
> The essence is wrapping something the code up in a kind of RAII-like
> entry and exit code that references a given target variable.
[...]

Kinda ugly-looking, but here's the first idea that came to mind:

	bitmap* b;
	{
		set_target_bitmap(b);
		scope(exit) set_target_bitmap(original_target);

		draw_pixel(...);
		... // blah blah blah
	} // scope(exit) runs here


T

-- 
Unix was not designed to stop people from doing stupid things, because that would also stop them from doing clever things. -- Doug Gwyn