D isn't the only language with janky closure semantics

[H. S. Teoh]

On Fri, Aug 29, 2025 at 10:51:10PM +0000, Steven Schveighoffer via Digitalmars-d wrote:
> On Friday, 29 August 2025 at 22:28:17 UTC, H. S. Teoh wrote:
> > Now, JS is certainly not a model language to follow, but it's
> > interesting how it shares with D the same issue over closures
> > involving loop variables.
> > 
> > I guess that means we're not alone. :-P  Even though this situation
> > is definitely not ideal.
> 
> Oh yeah, JS has similar behavior. You get the desired behavior by
> using `let` at the variable declaration. Otherwise, it becomes a
> regular declaration (one instance per function).
> 
> I think your original code will work as you want with:
> 
> ```js
> for (let button of buttons) {
> ```

Oooh yes, that *is* exactly what I was looking for.  I already got
bitten before by for(... of) without `let`... still haven't learned my
lesson, it seems.


> Would be nice to have a similar trick for D...

Sneaky syntax proposal:

```d
	void delegate()[] dgs;
	foreach (scope i; 0 .. 100) {	// N.B. `scope`
		dgs ~= () {
			writefln("%d", i); // <-- closes over independent instance of `i`
		};
	}
```

;-)


T

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