> On Nov 2, 2023, at 1:44 PM, Sven Barth <[email protected]> wrote:
>
> Now for nested as well as anonymous routines the compiler determines whether
> a capturer is required at the point that the nested or anonymous routine is
> assigned to a function reference (cause otherwise it can be handled as a
> nested function or even a function or method pointer). This requirement is
> detected during the parsing of the routine.
On second thought I had some questions about this part. From what I see FPC
always allocates the interface when reference pointers are used but what you
write suggests maybe the compiler will demote the type to something more
optimized (like a nested function). We talked about this at length before but I
don't think anything was decided yet.
for example:
procedure DoThis;
var
proc: reference to procedure;
begin
proc := procedure
begin
end;
proc();
end;
doesn't need the heap allocated instance because the function reference never
escapes the scope and it has no captured variables so it could be demoted to a
global function even of nested.
In fact Swift requires you to mark closures types as "@escaping" if they can
escape the current scope so that the compiler can be optimize them. This is the
feature I was thinking FPC needs.
Can you clarify this?
Regards,
Ryan Joseph
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