Yes there is, but it only does code editor commands. It’s been there since at least 1998 (read Delphi 4), probably all 32-bit versions and maybe even the 16-bit Delphi 1 version.
Generics and constraints in Delphi is still a bit of pain.
A while ago, I needed a factory for threads. It was more convoluted than I meant it to be, so I had a short chat with Stefan Glienke.
He came up with an example similar to the one below. I tore it apart so you can on each line see what the compiler dislikes.
This fails, but was kind of how I wanted it to be:
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;
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;
The usage:
var
Component: TButton;
Owner: TComponent;
begin
Owner := Application.MainForm;
Component := TComponentFactory<TButton>.CreateComponent(Owner);
Component.Parent := Owner;
end;
In the mean time, Spring4D has added the [Archive.is] Spring4D: TActivator record with many CreateInstance methods that allow you to create instances of classes for which you just have type information.
–jeroen
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;
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So I’ve been working on a GExperts based solution (because that gave me a nice starting point). It’s not fully done yet, so here are a few things I’ve used:
The streaming mechanism looks for published methods in the RTTI that have a name equal to the event in the stream and a signature matching the event type.The default section by definition has visibility published for anything compiled in $M+ mode (which is enabled for TPersistent and inherits to descendants).
The Wiert Corner - irregular stream of stuff 