[fpc-devel]TReader.ReadPropValue

[Mattias Gaertner]

On Fri, 5 Dec 2003 19:06:12 +0100  "Darek Mazur" <darekm at emadar.com> wrote:

> I've try to discover why LRS don't work with TColor, and I think I found:
> 
> in ReadPropValue for enumeration identifier can't be a VALUE
> 
> this is my proposition to solve:
> 
>     tkEnumeration:

- TColor is not an enum
- Even FindIdentToInt will fail, for the simple reason that the
ColorToInt/IntToColor functions can't be found. These functions are
registered by the return value of TypeInfo(TColor), which should return one
unique pointer for each type. But fpc 1.0.x and 1.9.x returns different
values, depending on where you use the TypeInfo function. In this case:
TypeInfo(TColor) called in graphics.pp returns a different value than called
in classes.pp.
One solution would be to add a further list of IntToIdent functions
identified by names instead of TypeInfo. The disadvantage is, that it can be
ambgious. But since the TypeInfo registering does not work, it is not used,
so this workaround will not break any code. And what is more important:
These things are rarely used, so as soon as the TypeInfo works, we only need
to change a few lines of code.


About the addition: I think, it can be useful for alias enums (e.g. myenum =
(a:=b, c:=d, ...) ). What do the fpc devels think about?


Mattias



>       begin
>         Value := GetEnumValue(PropType, ReadIdent);
>         if value = -1 then begin
>           IdentToIntFn := FindIdentToInt(PPropInfo(PropInfo)^.PropType);
>           Ident := ReadIdent;
>           if Assigned(IdentToIntFn) then IdentToIntFn(Ident, Value);
>         end;
> 
>         if Value = -1 then
>           raise EReadError.Create(SInvalidPropertyValue);
>         SetOrdProp(Instance, PropInfo, Value);
>       end;
> 
> 
> Darek
> 
> 
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