As python programmer, I love the elegant way to tweak function behaviours with decorators.
In order not to be executed when another profile is invoked, most setup handler functions must start with:
def setupSomeStuff(context):
if context.readDataFile("mysite.txt") is None:
return
# Let's do the job baby
...
return
As the site I’m working on needs a lot of handlers that are used in various conditions like this one. But there are lots of such…
<gs:importStep
name="Products.MySite.setupSomeStuff"
title="Stuff that site"
description="D'ya know what stuffing means..."
handler="Products.MySite.setuphandlers.setupSomeStuff">
<depends name="Products.MySite.importSiteStructure" />
</gs:importStep>
…and of course as many setup handler functions.
In order to shorten a little bit the code, I made a simple decorator that executes the setup handler only in the context of the extension profile. Should be fine.
def thisProfileOnly(func):
"""Decorator that prevents the setup func to be used on other GS profiles.
Usage:
@thisProfileOnly
def someFunc(context): ...
"""
def wrapper(context):
if context.readDataFile('mysite.txt') is None:
logger.info("*NOT* Executing setuphandler function %s", func.__name__)
return
else:
logger.info("Executing setuphandler function %s", func.__name__)
return func(context)
@thisProfileOnly
def setupSomeStuff(context):
# Let's do the job baby
...
return
Let’s go baby… But wait… It does not work! Importing the profile doe not run the setup handlers.
Having a deeper look into all this, I found that the relevant GenericSetup registry does hold the decorated functions but the unbound wrapper itself. Bad news.
Is it a bug or a feature? Anyway, digging in the Python gurus blogs, I found how to work this around, augmenting the wrapper such it gets most of the decorated function signature. Follow the lines in red in the fixed decorator.
def thisProfileOnly(func):
"""Decorator that prevents the setup func to be used on other GS profiles.
Usage:
@thisProfileOnly
def someFunc(context): ...
"""
def wrapper(context):
if context.readDataFile('modulo.txt') is None:
logger.info("*NOT* Executing setuphandler function %s", func.__name__)
return
else:
logger.info("Executing setuphandler function %s", func.__name__)
return func(context)
wrapper.__name__ = func.__name__
wrapper.__dict__.update(func.__dict__)
wrapper.__doc__ = func.__doc__
wrapper.__module__ = func.__module__
return wrapper
Yes, with such decorators, you may use decorated functions in your ZCML.
Note that this should be useless from Python 2.5, but I didn’t test in such situation (too lazy to try to run the Zope/Plone machinery with Python 2.5)
Other sources about advanced Python decorators:
