RFC: arbitrary transformation for renderables

[Роман Донченко]

Hello,

I wrote a class to simplify transforming renderables with arbitrary  
functions. I think it's useful enough to include in Buildbot itself. What  
do you think?

class Transform(object):
     implements(IRenderable)

     def __init__(self, function, *args, **kwargs):
         self.function = function
         self.args = args
         self.kwargs = kwargs

     @defer.inlineCallbacks
     def getRenderingFor(self, iprops):
         rfunction = yield iprops.render(self.function)
         rargs = yield iprops.render(self.args)
         rkwargs = yield iprops.render(self.kwargs)
         defer.returnValue(rfunction(*rargs, **rkwargs))

Example uses:

Transform(lambda: datetime.date.today().isoformat()) # get build date as a  
renderable
Transform(os.path.realpath, Property('builddir'))
Transform(os.path.relpath, my_file, start=Property('builddir'))

Roman.