Using inherited in the "Create" constructor of an TObject

Question

Should I call "inherited" in the constructor of a class derived from TObject or TPersistent?

constructor TMyObject.Create;
begin
 inherited Create;   // Delphi doc: Do not create instances of TPersistent. Use TPersistent as a base class when declaring objects that are not components, but that need to be saved to a stream or have their properties assigned to other objects.    
 VectorNames := TStringList.Create;
 Clear;
end;

Answer 1

Yes. It does nothing, true, but it's harmless. I think there is value in being consistent about always calling the inherited constructor, without checking to see if there is, in fact, an implementation. Some will say that it's worth calling inherited Create because Embarcadero might add an implementation for TObject.Create in the future, but I doubt this is true; it would break existing code which does not call inherited Create. Still, I think it is a good idea to call it for the reason of consistency alone.

Answer 2

I always does this.

If you are refactoring and move code to a common ancestor, calling the inherited Create has the follwoing advantages:

1. If the common ancestor has a constructor, you can't forget to call it.
2. If the common ancestor has a constructor with different parameters, the compiler warns you for this.

Answer 3

You can also override "procedure AfterConstruction". This procedure is always called, no matter what kind of constructor.

public
  procedure AfterConstruction; override;
end;

procedure TfrmListBase.AfterConstruction;
begin
  inherited;
  //your stuff, always initialized, no matter what kind of constructor!
end;

For example: if you want to create an object with a different constructor than the normal TObject.Create, such as TComponent.Create(AOwner) or a custom (overloaded) constructor, you can get problems because your override is not called and (in this case) your "VectorNames" variable will be nil.

Answer 4

I call it, except when i need a very optimized constructor.