On Mon, 17 May 2010 10:05:27 +0100 Martin <f...@mfriebe.de> wrote: > On 14/05/2010 15:52, Mattias Gaertner wrote: > > "var" means, you can do this: > > > > type > > TQStrings = class(TStrings) > > end; > > > > procedure A(var s: TStrings); > > begin > > s:=TQStrings.Create; > > end; > > > > Then your TStringList will no longer be a TStringList. That's why 'var' > > must match exactly. > > Same for out. > > Const and no modifier allows to pass descendants. > > > > yes, true, then if we follow that consequently: > > > procedure Foo(out s: TStrings); > begin > end; > > var x: TObject; > foo(x); > > should work? (or well only if it is made sure, that out really means > out, so the procedure is not allowed to use the value that was passed in) > > "s" can be assigned a TStrings (or descendant of) => which should be > fine, since it can be stored in x too.
Theoretically: yes, this could work for classes. But as Jonas explained a few times: 'out' is *not* write only. Out is finalised and must therefore match exactly. And even write-only is not enough for "object"s because an ancestor has too less memory. Mattias _______________________________________________ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
