python-dependency-injector/objects/std_providers.py
2015-01-04 16:26:33 +02:00

109 lines
2.2 KiB
Python

"""
Standard providers.
"""
class Provider(object):
"""
Base provider class.
"""
def __call__(self, *args, **kwargs):
"""
Returns provided instance.
"""
raise NotImplementedError()
class NewInstance(Provider):
"""
New instance providers will create and return new instance on every call.
"""
def __init__(self, provides, **dependencies):
"""
Initializer.
"""
self.provides = provides
self.dependencies = dependencies
def __call__(self, *args, **kwargs):
"""
Returns provided instance.
"""
for name, dependency in self.dependencies.iteritems():
if name in kwargs:
continue
if isinstance(dependency, Provider):
value = dependency.__call__()
else:
value = dependency
kwargs[name] = value
return self.provides(*args, **kwargs)
class Singleton(NewInstance):
"""
Singleton provider will create instance once and return it on every call.
"""
def __init__(self, *args, **kwargs):
"""
Initializer.
"""
self.instance = None
super(Singleton, self).__init__(*args, **kwargs)
def __call__(self, *args, **kwargs):
"""
Returns provided instance.
"""
if not self.instance:
self.instance = super(Singleton, self).__call__(*args, **kwargs)
return self.instance
class _StaticProvider(Provider):
"""
Static provider is base implementation that provides exactly the same as
it got on input.
"""
def __init__(self, provides):
"""
Initializer.
"""
self.provides = provides
def __call__(self):
"""
Returns provided instance.
"""
return self.provides
class Class(_StaticProvider):
"""
Class provider provides class.
"""
class Object(_StaticProvider):
"""
Object provider provides object.
"""
class Function(_StaticProvider):
"""
Function provider provides function.
"""
class Value(_StaticProvider):
"""
Value provider provides value.
"""