This is a copy of a post on the macpascal mailing list, where it was suggested to re-ask on the
fpc-devel list.
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The RTTI generating logic in the FPC compiler puzzles me ....
Chapter 40 of FreePascal Run-Time Library Reference guide describes the typinfo
unit. It says
; The TypeInfo unit contains many routines which can be used for the querying
of the Run-Time
; Type Information (RTTI) which is generated by the compiler for classes that
are compiled under the
; {$M+} switch
Great so far !
; This information can be used to retrieve or set property values for published
properties
; for totally unknown classes. In particular, it can be used to stream classes
This is what I fail to understand. Why is RTTI information tied to properties
and why is it
restricted to what is in the published/public sections of classes (or objects
in macpas mode) ? For
example, when I want to implement an object browser for debugging purposes, I
want to see anything.
What I am allowed in the code to do with the methods and fields is irrelevant
and whether fields
are properties or not is irrelevant too.
When I try it, $M+ refuses public non-property class fields. With $M-
ClassInfo, GetTypeData and
the ParentInfo field work. However, FieldAddress and MethodName do not work.
The field count in the
FieldTable field of the VMT is 0.
Is there a special reason why the compiler can't fill in the VMT's FieldTable ?
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Jonas Maebe replied that RTTI information has been implemented according to Delphi conventions.
Marco van de Voort mentioned D2010 and work being done on the extended RTTI ($RTTI directive). Paul
Ishenin remembered Joost implemented some prototype in a branch, that had some problems and was
not merged to trunk yet.
Regards,
Adriaan van Os
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