delphi 7 Items property

Question

I come from Java background, where we have data structures with interfaces that if its collection it support certain behaviour, and a set has another.

while programming in Delphi I thed to hit a brick wall when it comes in asking the reflection about the behaviour of items, its very strange. for example this code does not compile

      menuOfSomeKind.Items.Add(t);

where menu of some kind is a component that has Items that contain other sub components, that are the menu entries.

if I want to dynamically edit this, meaning using the add behaviour, it says '[' expected but '.' found.

Could you please clarify this?

Answer 1

Probably menuOfSomeKind is TMenuItem and not TMainMenu

If you are adding an item to TMenuItem use MenuItem.Add(t);

If you are adding an item to TMainMenu use MainMenu.Items.Add(t);

Answer 2

There's a difference between TMainMenu/TMenu and TMenuItem.

var
  mainMenu: TMainMenu;
  menu: TMenu;
  subMenu: TMenuItem;
begin
  //***** This creates a new root menu
  mainMenu.Items.Add(TMenuItem.Create);

  //***** Essentially the same as mainMenu
  menu.Items.Add(TMenuItem.Create)

  //***** This adds a new submenu to an existing menu
  subMenu.Add(TMenuItem.Create);

  //***** This adds a new submenu to the first submenu of an existing menu
  subMenu.Items[0].Add(TMenuItem.Create);
end;

Note that presented code compiles but will throw exceptions all over the place when run. For starters, none of the local variables are assigned.