collective.monkeypatcher 1.0a1

Support for applying monkey patches late in the startup cycle by using ZCML configuration actions

Introduction

Sometimes, a monkey patch is a necessary evil.

This package makes it easier to apply a monkey patch during Zope startup. It uses the ZCML configuration machinery to ensure that patches are loaded “late” in the startup cycle, so that the original code has had time to be fully initialised and configured. This is similar to using the initialize() method in a product’s __init__.py, except it does not require that the package be a full-blown Zope 2 product with a persistent Control_Panel entry.

Here’s an example:

<configure
    xmlns="http://namespaces.zope.org/zope"
    xmlns:monkey="http://namespaces.plone.org/monkey"
    i18n_domain="collective.rooter">

    <include package="collective.monkeypatcher" file="meta.zcml" />

    <monkey:patch
        class="Products.CMFPlone.CatalogTool.CatalogTool"
        original="searchResults"
        replacement=".catalog.patchedSearchResults"
        />

</configure>

In this example, we patch Plone’s CatalogTool’s searchResults() function, replacing it with our own version in catalog.py. To patch a module level function, you can use ‘module’ instead of ‘class’. The original class and function/method name and the replacement symbol will be checked to ensure that they actually exist.

If patching happens too soon (or too late), use the ‘order’ attribute to specify a higher (later) or lower (earlier) number. The default is 1000.

If you want to do more than just replace one function with another, you can provide your own patcher function via the ‘handler’ attribute. This should be a callable like:

def apply_patch(scope, original, replacement):
    ...

Here, ‘scope’ is the class/module that was specified. ‘original’ is the string name of the function to replace, and ‘replacement’ is the replacement function.

Changelog

1.0b1 - 2009-03-29

• Initial release