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.
Applying a monkey patch
Here's an example:
<configure xmlns="http://namespaces.zope.org/zope" xmlns:monkey="http://namespaces.plone.org/monkey" i18n_domain="collective.monkeypatcher"> <include package="collective.monkeypatcher" /> <monkey:patch description="This works around issue http://some.tracker.tld/ticket/123" 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.
By default, DocFinderTab and other TTW API browsers will emphasize the monkey patched methods/functions, appending the docstring with "Monkey patched with 'my.monkeypatched.function'". If you don't want this, you could set the docstringWarning attribute to false.
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.
Full list of options:
classThe class being patched
moduleThe module being patched
handlerA function to perform the patching. Must take three parameters: class/module, original (string), and replacement
originalMethod or function to replace
replacementMethod or function to replace with
preserveOriginalPreserve the original function so that it is reachable view prefix _old_. Only works for default handler
preconditionsPreconditions (multiple, separated by space) to be satisified before applying this patch. Example: Products.LinguaPlone-=1.4.3 or Products.TextIndexNG3+=3.3.0
ignoreOriginalIgnore if the orginal function isn't present on the class/module being patched
docstringWarningAdd monkey patch warning in docstring
descriptionSome comments about your monkey patch
Handling monkey patches events
Applying a monkey patch fires an event. See the interfaces.py module. If you to handle such event add this ZCML bunch:
... <subscriber for="collective.monkeypatcher.interfaces.IMonkeyPatchEvent" handler="my.component.events.myHandler" /> ...
And add such Python:
def myHandler(event): """see collective.monkeypatcher.interfaces.IMonkeyPatchEvent""" ...