magic cookie
1. Something passed between routines or programs that enables the receiver to
perform some operation; a capability ticket or opaque identifier. Especially
used of small data objects that contain data encoded in a strange or
intrinsically machine-dependent way. E.g. on non-Unix operating systems with a
non-byte-stream model of files, the result of "ftell" may be a magic cookie
rather than a byte offset; it can be passed to "fseek", but not operated on in
any meaningful way. The phrase "it hands you a magic cookie" means it returns a
result whose contents are not defined but which can be passed back to the same
or some other program later.
2. An in-band code for changing graphic rendition (e.g. inverse video or
underlining) or performing other control functions. Some older terminals would
leave a blank on the screen corresponding to mode-change magic cookies; this was
also called a glitch (or occasionally a "turd"; compare mouse droppings).
See also cookie.
[Jargon File]
(1995-01-25)
Nearby terms:
MAGIC « magic « magic bullet « magic cookie »
magic number » Magic Paper » magic smoke
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