Class Let

source code

object --+
         |
        Let

A Let allows for temporarily storing passed arguments in the _settings
member of a target object for the duration of the contextmanager's scope

Implementation on a factory class

class MyThingFactory(object):
    def __init__(self):
        self._settings = {}
    def generate_thing(self):
        # do something here
        new_obj = Thing()
        for k,v in self._settings.iteritems():
            setattr(new_obj, k, v)
        return new_obj
    def let(self, **kwds):
        return Let(self, kwds)

Calling code that wants to temporarily customize the Thing objects that are
returned by the factory:

fac = MyThingFactory()
with fac.let(this="that", foo="bar"):
    a_thing = fac.generate_thing()
    self.assertEqual(a_thing.this, "that")