delphi - Create generic class or interface with self typed parameters in children classes -


i'd create class or interface subclass, using current class instances methods parameters...

here example explain problem:

 type iarithmeticobject = interface(iinterface)    procedure assign(ao : iarithmeticobject);    procedure add(ao : iarithmeticobject);    procedure remove(ao : iarithmeticobject);    procedure multiply(ao : iarithmeticobject);    procedure divide(ao : iarithmeticobject);  end;

the interface iarithmeticobject whould starting point, referencing basic arithmetic operations , child classes declared as

 type tinteger = class(tinterfacedobject, iarithmeticobject)    procedure assign(ao : tinteger);    procedure add(ao : tinteger);    procedure remove(ao : tinteger);    procedure multiply(ao : tinteger);    procedure divide(ao : tinteger);  end;

with parameter type ao being tinteger , not iarithmeticobject.

another idea use self referencing generic type like:

  amathobject = class;    amathobject<t : amathobject, constructor> = class     procedure assign(ao : t);virtual;abstract;     procedure add(ao : t);virtual;abstract;     procedure remove(ao : t);virtual;abstract;     procedure multiply(ao : t);overload;virtual;abstract;     procedure divide(ao : t);virtual;abstract;   end;

but not figure out right syntax...

does have ideas possibility (or impossibility)?

if undestand correctly, may want derive class generic interface.

type   iarithmeticobject<t> = interface     procedure assign(ao: iarithmeticobject<t>);     procedure add(ao: iarithmeticobject<t>);     procedure remove(ao: iarithmeticobject<t>);     procedure multiply(ao: iarithmeticobject<t>);     procedure divide(ao: iarithmeticobject<t>);   end;    tinteger = class (tinterfacedobject, iarithmeticobject<tinteger>)     procedure assign(ao: iarithmeticobject<tinteger>);     procedure add(ao: iarithmeticobject<tinteger>);     procedure remove(ao: iarithmeticobject<tinteger>);     procedure multiply(ao: iarithmeticobject<tinteger>);     procedure divide(ao: iarithmeticobject<tinteger>);   end;

answer edited according stefan glienke's comment: methods of class accept parameters declared either objects or interfaces.

var   ao: iarithmeticobject<tinteger>; begin   ao := tinteger.create;   ao.multiply(ao); end.

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