[fpc-pascal] Read Field names from VMT

[Amir at Aavani.net]

How can I set the value?
I tried something like

Test := TTest.Create

Ptr := Pointer(Test);
TSub(Ptr+8) := TSub.Create;

But it is not working?
> You can use the PVmtFieldTable and PVmtFieldEntry types from the 
> TypInfo unit:
>
> === code begin ===
>
> program tfield;
>
> {$mode objfpc}{$H+}
>
> uses
>   TypInfo;
>
> type
>   {$M+}
>   TSub = class
>
>   end;
>
>   TTest = class
>   published
>     fTest: TSub;
>   end;
>
> var
>   vft: PVmtFieldTable;
>   vfe: PVmtFieldEntry;
>   i: SizeInt;
> begin
>   vft := PVmtFieldTable(PVMT(TTest)^.vFieldTable);
>   Writeln(vft^.Count, ' field(s) with ', vft^.ClassTab^.Count, ' 
> type(s)');
>   for i := 0 to vft^.Count - 1 do begin
>     vfe := vft^.Field[i];
>     Writeln(i, ' -> ', vfe^.Name, ' @ ', vfe^.FieldOffset, ' of type 
> ', vft^.ClassTab^.ClassRef[vfe^.TypeIndex - 1]^.ClassName);
>   end;
> end.
>
> === code end ===
>
> === output begin ===
>
> PS C:\fpc\git> .\testoutput\tfield.exe
> 1 field(s) with 1 type(s)
> 0 -> fTest @ 8 of type TSub
>
> === output end ===
>
> Side note: contrary to what I had originally written only classes, but 
> not interfaces are allowed for published fields and they need to have 
> $M enabled.
>
> Regards,
> Sven
>
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