does a class property or a variable exist

[alnickels 0]

Is there a way to tell if a variable or class property exist within delphi at runtime?

[David Heffernan 2345]

These things are determined at compile time. You can't declare either at run time. So why do you feel this a run time issue? 

[aehimself 396]

Yes, it does (but I don't know since when):

 

Type
 TMyClass = Class
 public
  Class Var Counter: Integer;
  Constructor Create; ReIntroduce;
 End;

Constructor TMyClass.Create;
Begin
 Inc(Self.Counter);
End;

Procedure TForm1.Button1Click(Sender: TObject);
Var
 v1, v2: TMyClass;
Begin
 v1 := TMyClass.Create;
 v2 := TMyClass.Create;
 ShowMessage(IntToStr(TMyClass.Counter)); // Will show 2
End;

 

[Remy Lebeau 1394]

45 minutes ago, alnickels said:

Is there a way to tell if a variable or class property exist within delphi at runtime?

Are you looking for an RTTI solution to detect at run-time whether or not a given class type has declared a given class variable/property at compile-time?  What is the end goal here that you are trying to accomplish?

Edited September 1, 2020 by Remy Lebeau

[alnickels 0]

Remy that will work.    The application will read xml and get a variable or property name.  If variable or property exists we will take certain actions depending on its value.

 

[Remy Lebeau 1394]

1 hour ago, alnickels said:

Remy that will work.    The application will read xml and get a variable or property name.  If variable or property exists we will take certain actions depending on its value.

Well, that is pretty easy to accomplish using TRttiContext.GetType() or TRttiContext.FindType(), and then using TRttiType.GetField() and TRttiType.GetProperty().

Edited September 1, 2020 by Remy Lebeau

[Stefan Glienke 2002]

RTTI does not contain any information about class properties or vars/fields 

 

For clarification please see my P.S. in this post.

[alnickels 0]

Thank you very much Remy Lebeau