[fpc-pascal] How can I get a typeinfo by address?

silvioprog silvioprog at gmail.com
Fri Jul 17 16:13:06 CEST 2015


Hello,

I need to call a method dynamically by its name over string and pass some
parameters to it. OK, I don't know if it is possibly in the current version
of the compiler, but I'm trying to do something like this:

TMethodInvoker.Invoke(VMyObj, ['Param 1', 'Param 2', 1, True]);

I already get some paramerter informations using this code[1], that prints
all parameters and its types using RTTI.

So I have a question: how can I get the method typedata looking for it in
the VMT? Please see this:

  WriteLn(HexStr(@TMyObject.Test));
  WriteLn(HexStr(TMyObject.MethodAddress('Test')));

Prints the same address. But:

  TI := TypeInfo(@TMyObject.Test);
  WriteLn(HexStr(TI));
  TI := TypeInfo(TMyObject.MethodAddress('Test'));
  WriteLn(HexStr(TI));

Prints different results.

How System.TypeInfo retrieve the typeinfo from my @TMyObject.Test address?
It is done by the method address so?

I took a look at the TRTTIWriter class and also in the VMT, but I don't
know how the compiler handles this informations internally, so sorry it
this question sounds nonsense. =P

[1] - http://pastebin.com/bPascrwe

-- 
Silvio Cl├ęcio
My public projects - github.com/silvioprog
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