How to Convert a Native PM Item to OCL

Most native PM windows have an equivalent in OCL, and an item that already exists on a window can at any time be "converted" to OCL. This is advantageous for example if some of the functionality you need has already been implemented using OCL. For example:

> Can a pointer to a 'low-level' listbox be converted into a pointer to an > Open Class listbox? Dave Briccetti (daveb@davebsoft.com) says: Most of the OC UI controls have a constructor that takes the HWND of an existing control. In this case, the constructor looks like IListBox (const IWindowHandle &) IWindowHandle is an "alias" for HWND. Bill Law (law@netscape.com) also adds the following: Perhaps you should add that if an OCL window already exists for a given HWND, then constructing another one from its HWND will result in an exception being thrown. Generally, if there is a chance that an existing OCL window exists (or you know that one does and you just want to locate it), then you can use IWindow::fromHandle to get the existing IWindow (or derived-class) object. If that returns 0, then you can safely construct another IWindow (or derived-class) object.
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Page generated by Stéphane Charette on 1997 November 02
Open Class Library (OCL) FAQ © Stéphane Charette, 1997