[fpc-pascal] Caller agnostic procedure variables
Michael Van Canneyt
michael at freepascal.org
Tue Feb 15 15:21:32 CET 2022
On Tue, 15 Feb 2022, Ryan Joseph via fpc-pascal wrote:
>
>
>> On Feb 15, 2022, at 8:26 PM, Sven Barth via fpc-pascal <fpc-pascal at lists.freepascal.org> wrote:
>>
>> It's relatively "easy" to implement assigning a nested function to function references. However assigning a nested function variable to a function reference is much harder.
>> Assigning a function reference to a nested function variable is hard as well.
>>
>
> I'm getting lost with the terms now I think.
> If your function takes a function reference parameter and you assign it a nested function pointer,
> this is difficult? I believe this was Michaels request in that code snippet.
Sven will need to confirm, but as I understand it:
Procedure DoDemo(aTest : TProc);
Procedure MyTest;
Procedure DoSub;
begin
end;
begin
DoDemo(DoSub)
end;
is easy.
but
Procedure DoDemo(aTest : TProc);
Procedure MyTest;
Var
ASub : procedure is nested;
begin
aSub:=SomeFunctionThatReturnsANestedProc;
DoDemo(aSub);
end;
is difficult.
Michael.
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