I've got a base class defined:

        TBaseClass = class of TBase;
        TBase = class
                ...
        public
                constructor Create;
                class procedure New(...);
                ...
        end;

and several derived classes:

        TDerivedA = class(TBase)
                ...
        public
                constructor Create; override;
                ...
        end;

        TDerivedB = class(TBase)
                ...
        public
                constructor Create; override;
        end;

Note that none of the derived classes have overriden the "New" method, which
is defined as:

        class procedure TBase.New(...);
        var
                NewDerived: TBaseClass;
        begin
                NewDerived := Self.Create;
                ...
        end;

When I call, for example, TDerivedA.New(...), the TBase.New method is called
and the _class reference_ Self correctly shows a class type of TDerivedA.  
However, Self.Create doesn't call TDerivedA.Create, rather TBase.Create is
called.

Anyone know why this isn't working?  Incidently I (successfully) did something
quite similar to this in Delphi 1.0, where my TBase class was derived from
TForm.  Then given a string, S,  which was the class name of a derived class,
I did something akin to:

        var
                ClassRef: TPersistentClass;
                NewDerived: TBase;
        begin
                ClassRef := GetClass(S); {'TDerivedA', for example)
                NewDerived := TBaseClass(ClassRef).Create(...);
                ...
        end;

Any ideas would be appreciated.

TIA,
Gerard

Gerard M. Averill
Assistant Researcher

Center for Health Systems Research and Analysis
University of Wisconsin, Madison
E-mail: gaver...@chsra.wisc.edu

Never mind....  As it turned out, my derived Create methods were not declared
with "override", nor my base class Create with "virtual".  Adding these
directives solved the problem. ;)

G.

Gerard M. Averill
Assistant Researcher

Center for Health Systems Research and Analysis
University of Wisconsin, Madison
E-mail: gaver...@chsra.wisc.edu

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Jolyon Smith                         |  The views represented above are my own
Application Development Consultant   |  and do not necessarily represent the
PLATINUM Solutions (UK)              |  views of my employer.