Am 05.01.2012 11:57, schrieb kyan:
Hello everybody.
I am new to FPC/Lazarus and I am trying to port some Delphi XE code
that uses the units Generics.Defaults and Generics.Collections so I
have to write these units for FPC because they do not exist and the
code I am porting relies heavily on them. In this process I have come
across various issues with Delphi/FPC generic compatibility but I have
managed to overcome most of them.
If there are compatibility problems that are not yet mentioned in the
bugtracker at http://bugs.freepascal.org/ it would be nice if you'd
report them.
In a method of a generic class I need to initialize a variable of type
"T" (the generic class type parameter) with the type T's "default"
value, which is 0 for ordinal types, '' for strings, nil for
pointers/classes/interfaces, Unassigned for Variants etc. In Delphi
there is the "compiler magic" function Default() and you can write:
procedure TMyClass<T>.SomeMethod;
var
V: T;
begin
...
V := Default(T);
...
end;
This does not compile in FPC. Is there an alternative in FPC for the
function Default()? I suppose one could do this:
This functionality does not exist yet. See also here:
http://bugs.freepascal.org/view.php?id=9420
procedure TMyClass<T>.SomeMethod;
var
V: T;
begin
...
Finalize(V);
FillChar(V, SizeOf(V), 0);
...
end;
which is equivalent but it doesn't look too elegant. I am using FPC
2.7.1 for Win32/64.
For now you'll need to use this workaround solution.
Regards,
Sven
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