2014-04-26 10:52:28 -04:00
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hook
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2014-04-26 11:54:15 -04:00
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n. A software or hardware feature included in order to simplify later
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additions or changes by a user. For example, a simple program that prints
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numbers might always print them in base 10, but a more flexible version
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would let a variable determine what base to use; setting the variable to 5
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would make the program print numbers in base 5. The variable is a simple
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hook. An even more flexible program might examine the variable and treat a
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value of 16 or less as the base to use, but treat any other number as the
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address of a user-supplied routine for printing a number. This is a hairy
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but powerful hook; one can then write a routine to print numbers as Roman
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numerals, say, or as Hebrew characters, and plug it into the program through
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the hook. Often the difference between a good program and a superb one is
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that the latter has useful hooks in judiciously chosen places. Both may do
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the original job about equally well, but the one with the hooks is much more
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flexible for future expansion of capabilities ( EMACS , for example, is all
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hooks). The term user exit is synonymous but much more formal and less
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hackish.
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