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# Copyright (c) 2010 Mark Sandstrom
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
import threading
global_counter_lock = threading.Lock()
class GlobalCounter(object):
"""A simple global counter.
It is used to order the various OrderedDeclaration together.
"""
_value = 0
@classmethod
def step(cls):
with global_counter_lock:
current = cls._value
cls._value += 1
return current
class OrderedDeclaration(object):
"""A factory declaration.
Ordered declarations keep track of the order in which they're defined so that later declarations
can refer to attributes created by earlier declarations when the declarations are evaluated."""
_next_order = 0
def __init__(self):
self.order = GlobalCounter.step()
def evaluate(self, factory, obj):
"""Evaluate this declaration.
Args:
factory: The factory this declaration was defined in.
obj: The object holding currently computed attributes
attributes: The attributes created by the unordered and ordered declarations up to this point."""
raise NotImplementedError('This is an abstract method')
class LazyAttribute(OrderedDeclaration):
def __init__(self, function):
super(LazyAttribute, self).__init__()
self.function = function
def evaluate(self, factory, obj):
return self.function(obj)
class SelfAttribute(OrderedDeclaration):
def __init__(self, attribute_name):
super(SelfAttribute, self).__init__()
self.attribute_name = attribute_name
def evaluate(self, factory, obj):
return getattr(obj, self.attribute_name)
class Sequence(OrderedDeclaration):
def __init__(self, function, type=str):
super(Sequence, self).__init__()
self.function = function
self.type = type
def evaluate(self, factory, obj):
return self.function(self.type(factory.sequence))
class LazyAttributeSequence(Sequence):
def evaluate(self, factory, obj):
return self.function(obj, self.type(factory.sequence))
class SubFactory(OrderedDeclaration):
"""Base class for attributes based upon a sub-factory.
Attributes:
defaults: DeclarationsHolder, the declarations from the wrapped factory
factory: Factory, the wrapped factory
"""
def __init__(self, factory, **kwargs):
super(SubFactory, self).__init__()
self.defaults = kwargs
self.factory = factory
def evaluate(self, factory, create, extra):
"""Evaluate the current definition and fill its attributes.
Uses attributes definition in the following order:
- attributes defined in the wrapped factory class
- values defined when defining the SubFactory
- additional values defined in attributes
"""
defaults = dict(self.defaults)
if extra:
defaults.update(extra)
attrs = self.factory.attributes(create, defaults)
if create:
return self.factory.create(**attrs)
else:
return self.factory.build(**attrs)
# Decorators... in case lambdas don't cut it
def lazy_attribute(func):
return LazyAttribute(func)
def sequence(func):
return Sequence(func)
def lazy_attribute_sequence(func):
return LazyAttributeSequence(func)
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