Callback (Computer Programming)

Callback (Computer Programming)

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Description

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In computer programming, a callback is a reference to executable code, or a piece of executable code, that is passed as an argument to other code. This allows a lower-level software layer to call a subroutine defined in a higher-level layer. Callbacks have a wide variety of uses. For example, imagine a function that reads a configuration file and associates values with options. If the options are identified by a hash, then writing the function so that it takes a callback makes it more flexible: its user can choose whatever hashing algorithm is desired and the function will continue to work, since it uses the callback to turn option names into hashes; thus, callbacks allow the user of a function to fine-tune it at runtime. Another use is in error signaling. A Unix program, for example, might not want to terminate immediately when it receives SIGTERM; to make sure things get taken care of, it would register the cleanup function as a callback. Callbacks may also be used to control whether a function acts or not: Xlib allows custom predicates to be specified to determine whether a program wishes to handle an event.show more

Product details

  • Paperback | 76 pages
  • 152 x 229 x 5mm | 122g
  • Bellum Publishing
  • United States
  • English
  • 6136583933
  • 9786136583938