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(elisp)Computed Advice

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Computed Advice
===============

   The macro `defadvice' resembles `defun' in that the code for the
advice, and all other information about it, are explicitly stated in
the source code.  You can also create advice whose details are computed,
using the function `ad-add-advice'.

 - Function: ad-add-advice function advice class position
     Calling `ad-add-advice' adds ADVICE as a piece of advice to
     FUNCTION in class CLASS.  The argument ADVICE  has this form:

          (NAME PROTECTED ENABLED DEFINITION)

     Here PROTECTED and ENABLED are flags, and DEFINITION is the
     expression that says what the advice should do.  If ENABLED is
     `nil', this piece of advice is initially disabled (Note: Enabling
     Advice).

     If FUNCTION already has one or more pieces of advice in the
     specified CLASS, then POSITION specifies where in the list to put
     the new piece of advice.  The value of POSITION can either be
     `first', `last', or a number (counting from 0 at the beginning of
     the list).  Numbers outside the range are mapped to the beginning
     or the end of the range, whichever is closer.  The POSITION value
     is ignored when redefining an existing piece of advice.

     If FUNCTION already has a piece of ADVICE with the same name, then
     the position argument is ignored and the old advice is replaced
     with the new one.