RTTI in Delphi

Question

I'm trying to parse objects to XML in Delphy, so I read about calling the objet's ClassInfo method to get its RTTI info.

The thing is, this apparently only works for TPersistent objects. Otherwise, I have to specifically add a compiler directive {$M+} to the source code for the compiler to generate RTTI info.

So I happily added the directive, only to find that, even if it did return something from the ClassInfo call (it used to return nil), now I cannot retrieve the class' properties, fields or methods from it. It's like it created the object empty.

Any idea what am I missing here? Thanks!

Answer 1

RTTI will only show you published properties,etc. - not just public ones.

Try your code with a TObject and see what happens - if that isn't working, post your code because not everyone is psychic.

Answer 2

Did you put those properties and methods into the published section?

Besides that, 'classical' RTTI ($TYPEINFO ON) will only get you information on properties, not on methods. You need 'extended' RTTI ($METHODINFO ON) for those.

Good starting point for extended RTTI: David Glassborow on extended RTTI

(who would believe that just this minute I finished writing some code that uses extended RTTI and decided to browse the Stack Overflow a little:))

Answer 3

Have you considered using the TXMLDocument component? It will look at your XML and then create a nice unit of Delphi classes that represents your XML file -- makes it really, really easy to read and write XML files.