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A simple Inversion of Control container

Project description

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Installation

This library is a Python 3.2+ library.

Install it via pip for Python 3:

sudo pip3 install pymple

Usage

Pymple nows three types of parameters:

  • Values: A value is simply value that is saved and reused for all other factories/singletons

  • Singletons: A singleton is a callable that is executed once and the result is saved so future calls to the build method will return the same instance

  • Factories: A factory is callable that is executed again everytime it is accessed

from pymple import Container

# register simple values
container.register('value', 2)
container.build('value') == 2 # True

# register singletons
class MyClass:

    def __init__(self, value):
        self.value = value


container.register_singleton('MyClass', lambda x: MyClass(x.build('value')))
container.build('MyClass') == container.build('MyClass') # True
container.build('MyClass').value == 2 # True

# register factories (no instance will be saved)
container.register_factory('MyClass', lambda x: MyClass(x.build('value')))
container.build('MyClass') == container.build('MyClass') # False
container.build('MyClass').value == 2 # True

Using the @inject decorator

Instead of registering all values in the container, you can try to let the container assemble the class automatically

# in module some.module
class A:
    pass

# somewhere else
from pymple import Container

container = Container()
a = container.build('some.module.A')

from some.module.A import A
isinstance(a, A) # True

This works if the constructor is empty. If the constructor is not empty, the container needs a map from parameter value to container value as a static _inject attribute on the class. This attribute can be set with the @inject decorator:

from pymple import inject, Container

@inject(value='some.module.A', value2='param')
class C:

    def __init__(self, value, value2):
      self.value = value
      self.value2 = value2

container = Container()
container.register('param', 3)
c = container.build('module.file.C')

from some.module import A
isinstance(c.value, A) # True
c.value2 == 3 # True

Extending the container

You can also extend the container to make it reusable:

from pymple.container import Container

class MyContainer(Container):

    def __init(self):
        super().__init__()
        self.register('value', 3)


container = MyContainer()
container.build('value') == 3 # True

Project details


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