Shadow (OS/2)
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In the graphical Workplace Shell (WPS) of the OS/2 operating system, a shadow is an object that represents another object.
A shadow is a stand-in for any other object on the desktop, such as a document, an application, a folder, a hard disk, a network share or removable medium, or a printer. A target object can have an arbitrary number of shadows. When double-clicked, the desktop acts the same way as if the original object had been double-clicked. The shadow's context menu is the same as the target object's context menu, with the addition of an "Original" sub-menu, that allows the location of, and explicit operation upon, the original object.
A shadow is a dynamic reference to an object. The original may be moved to another place in the file system, without breaking the link. The WPS updates shadows of objects whenever the original target objects are renamed or moved. To do this, it requests notification from the operating system of all file rename operations. (Thus if a target filesystem object is renamed when the WPS is not running, the link between the shadow and the target object is broken.)
Shadows are similar in operation to aliases in Mac OS, although there are some differences:
- Shadows in the WPS are not filesystem objects, as aliases are. They are derived from the
WPAbstractclass, and thus their backing storage is the user INI file, not a file in the file system.[1] Thus shadows are invisible to applications that do not use the WPS API. - The WPS has no mechanism for re-connecting shadows when the link between them and the target object has been broken. (Although where the link has been broken because target objects are temporarily inaccessible, restarting the WPS after the target becomes accessible once more often restores the link.)
Shadows are different from symbolic links and shortcuts because they are not filesystem objects, and because shadows are dynamically updated as target objects are moved.
Shadows are different from hard links because unlike hard links they can cross volume boundaries and because their names are always the same as those of their target objects.
