After a discussion with Stefan Glienke: a pattern for a factory, this one for components, but can be uses for anything having a base class like a TThread descendant.

readme.md

This fails:

type
   TFactory = record
     class function Manufacture<T: TBaseClass, constructor>(parameter definitions): T;
   end;

class function Manufacture<T: TBaseClass, constructor>(parameter definitions): T;
begin
  Result := T.Create(parameter values);
end;

ComponentFactoryUnit.pas

type
  TComponentFactory = class
    class function CreateComponent<T: TComponent>(AOwner: TComponent): T; static;
  end;

class function TComponentFactory.CreateComponent<T>(AOwner: TComponent): T;
var
  ComponentClass: TComponentClass;
  Component: TComponent;
begin
  ComponentClass := T;
  Component := ComponentClass.Create(AOwner); // you can't do `T.Create(AOwner)`
  Result := T(Component); // you can't do `Result := ComponentClass.Create(AOwner);`
end;

ComponentFactoryUsageUnit.pas

var
  Component: TButton;
  Owner: TComponent;
begin
  Owner := Application.MainForm;
  Component := TComponentFactory<TButton>.CreateComponent(Owner);
  Component.Parent := Owner;
end;