delegate confusion

[bitwise via Digitalmars-d]

On Friday, 4 August 2017 at 17:18:41 UTC, Steven Schveighoffer 
wrote:
> On 8/4/17 12:57 PM, bitwise wrote:
>> [...]
>
> Because the stack frame of foo or bar or baz is stored on the 
> heap BEFORE the function is entered. The compiler determines 
> that the stack frame will need to be captured, so it captures 
> it on function entry, not when the delegate is taken. Then the 
> variable location is reused for the loop, and all delegates 
> point at the same stack frame.
>
> This is necessary for cases where the delegate may affect the 
> frame data during the function call. For instance:
>
> void foo()
> {
>    int i;
>    auto dg = { ++i;};
>    dg();
>    dg();
>    assert(i == 2);
> }
>
> What is needed is to allocate one frame per scope, and have the 
> delegate point at the right ones.
>
> Note, the C++ behavior uses dangling stack pointers, and not 
> something we want to support in D.
>
> -Steve

Thanks for clearing this up. Looking over my examples again, this 
makes sense now. I suppose while this behavior is not ideal, it 
does mean that I can safely throw lambdas that capture things 
into a queue to be executed later, which was my main concern.

I wish this forum was a little more advanced so I could change 
the post title I fudged and make this information more visible =/