Fórum Modurização com Packages usando Herança de formulários #295402

Class Inheritance
The first way to call your methods is to first define a base class that holds your method calls. This is the more traditional way of doing thing and generally works for all flavours of Delphi. 

For the purpose of illustration we´ll create a new form that we use as template called TForm2 in Unit2. Here we add custom methods as blank virtual methods (methods with no actual code in them) or as abstract virtual – in our example it´s a procedure called "MyCustomCall". This unit and form is then compiled into a package – in this case called Package1. This package then becomes our common package – our application will "compile with" it, and the dynamically loaded package will "require" it. 

Secondly we´ll create a new form (TForm3 in Unit3) that inherits from the template form (TForm2) and override the custom methods. We will also remember to call ´RegisterClass(TFrom3)´ in the unit´s initialization section. We then compile this unit and form into a new package that we will dynamically load (Package2). 

The application will then "compile with" Package1 and dynamically load Package2. To use our custom method we do something like this: 



var
  PackageModule: HModule;
  AClass: TPersistentClass;
begin
  PackageModule := LoadPackage(´Package2.bpl´);
  if PackageModule <> 0 then
  begin
    AClass := GetClass(´TForm3´);  // create inherited class

    if AClass <> nil then
      with TComponentClass(AClass).Create(Application)
        as TForm2 do  // type as base class
      begin
        MyCustomCall;  // the custom call here
        ShowModal;
        Free;
      end;

    UnloadPackage(PackageModule);
  end;
end;