On Fri, 7 May 2010 06:10:30 +0200
cobines <cobi...@gmail.com> wrote:
> 2010/5/6 spir ☣ <denis.s...@gmail.com>:
> > (By the way, started playing with TFPList already, and could not find how
> > to get data back! I mean the symtric of add(). Even tried indexing (who
> > knows, with the syntactic magic of modern language? ;-).)
>
> It is indexing.
>
> var
> l: TFPList;
> p: Pointer;
> index: Integer;
> begin
> l := TFPList.Create;
> index := l.Add(p);
> p := l[index];
> end;
> [...]
Thank you, I must have written a typo or messed up indices, since now it works
fine. Still, remains a mystery about untyped pointers, illustrated by the code
below:
var
l : TFPList;
i : Integer;
p : ^Integer;
begin
l := TFPList.Create;
i := 1 ; new(p) ; p^ := i; l.Add(p);
p := l[0] ; writeln(p^);
writeln(l[0]^); // error
end.
I cannot directly "fish" and use the pointer's target. Seems I always need to
pass _via_ the pointer, then all is fine. It's not really annoying. But I don't
understand the difference: in code, both versions are indeed strictly
equivalent. I guess there's an implicit (pointer?) conversion somewhere?
Are there cases where the pointer's mediation is not needed?
Denis
________________________________
vit esse estrany ☣
spir.wikidot.com
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