Package zope :: Package interface :: Module advice
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Module zope.interface.advice

Class advice.

This module was adapted from 'protocols.advice', part of the Python Enterprise Application Kit (PEAK). Please notify the PEAK authors (pje@telecommunity.com and tsarna@sarna.org) if bugs are found or Zope-specific changes are required, so that the PEAK version of this module can be kept in sync.

PEAK is a Python application framework that interoperates with (but does not require) Zope 3 and Twisted. It provides tools for manipulating UML models, object-relational persistence, aspect-oriented programming, and more. Visit the PEAK home page at http://peak.telecommunity.com for more information.

$Id: advice.py,v 1.2 2005/06/24 16:52:37 nyergler Exp $
Function Summary
  addClassAdvisor(callback, depth)
Set up 'callback' to be passed the containing class upon creation
  determineMetaclass(bases, explicit_mc)
Determine metaclass from 1+ bases and optional explicit __metaclass__
  getFrameInfo(frame)
Return (kind,module,locals,globals) for a frame
  isClassAdvisor(ob)
True if 'ob' is a class advisor function
  minimalBases(classes)
Reduce a list of base classes to its ordered minimum equivalent

Function Details

addClassAdvisor(callback, depth=2)

Set up 'callback' to be passed the containing class upon creation

This function is designed to be called by an "advising" function executed in a class suite. The "advising" function supplies a callback that it wishes to have executed when the containing class is created. The callback will be given one argument: the newly created containing class. The return value of the callback will be used in place of the class, so the callback should return the input if it does not wish to replace the class.

The optional 'depth' argument to this function determines the number of frames between this function and the targeted class suite. 'depth' defaults to 2, since this skips this function's frame and one calling function frame. If you use this function from a function called directly in the class suite, the default will be correct, otherwise you will need to determine the correct depth yourself.

This function works by installing a special class factory function in place of the '__metaclass__' of the containing class. Therefore, only callbacks *after* the last '__metaclass__' assignment in the containing class will be executed. Be sure that classes using "advising" functions declare any '__metaclass__' *first*, to ensure all callbacks are run.

determineMetaclass(bases, explicit_mc=None)

Determine metaclass from 1+ bases and optional explicit __metaclass__

getFrameInfo(frame)

Return (kind,module,locals,globals) for a frame

'kind' is one of "exec", "module", "class", "function call", or "unknown".

isClassAdvisor(ob)

True if 'ob' is a class advisor function

minimalBases(classes)

Reduce a list of base classes to its ordered minimum equivalent

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