[fpc-pascal] Streaming of Generics

[kyan]

> Ideally, I'd only like to write the streaming mechanism for each set
> of types (normal, anisstring, dynamic array, objects, interfaced
> objects) once, and use it for every set of items. However, there's no
> reasonable way to detect the type and do an execution for it. Ideally

You can use the "magic" function TypeInfo() to detect the type of a
generic parameter inside a method of a generic class. It returns a
PTypeInfo pointer so you can use PTypeInfo(TypeInfo(T))^ record to
determine the data type (Kind) -and other attributes- of the generic
type.

For the lack of generic procedures, you can substitute a generic
procedure with a generic class method:

type
  generic TStreamer<T> = class
  public
    procedure StreamType( Stream : TStream; Data : T );
  end;

procedure TStreamer.StreamType( Stream : TStream; Data : T );
begin
  case PTypeInfo(TypeInfo(Data))^.Kind of
    tkString:
      ...
    tkInteger:
      ..
  end;
end;

HTH

Constantine.