Scopeton

Scopeton is a simple dependency injection framework for Python inspired by the Java Spring framework

Main entities of the scopeton:

• Scope - the context of the application
• Bean - the small brick of the application to inject, can be singleton (default) or multiton

Installation

pip install scopeton

Basic usage

Firstly you have to create a scope and register beans there:

from scopeton import scope
class Dependency1:
    pass
class Dependency2:
    pass
class Dependency3:
    pass
appScope = scope.Scope()
appScope.registerBean(Dependency1, Dependency2, Dependency3)

There are several ways how to get the instance of dependency from the scope:

1. Service locator style:

    depencency1Instance = appScope.getInstance(Dependency1) - returns the singleton instance of Dependency1  

2. Automatic constructor injection:

from scopeton import scope
from scopeton.decorators import Inject

class Dependency1():
    pass

class Dependency4():
    pass

class Dependency5():
    @Inject()
    def __init__(self, dep1: Dependency1, dep4: Dependency4):
        pass


class Dependency7():
    called = False
    @Inject()
    def __init__(self, dep1:Dependency1, dep4: Dependency4):
        assert isinstance(dep1, Dependency1)
        assert isinstance(dep4, Dependency4)
        
appScope = scope.Scope()
appScope.registerBean(Dependency1, Dependency4, Dependency5, Dependency7)
instance = appScope.getInstance(Dependency7)

in this case the Dependency1 and Dependency4 will be injected automatically to the constructor of the Dependency7

Beans

The default bean configuration

appScope.registerBean(Dependency1, Dependency2, Dependency3)

configures beans Dependency1, Dependency2, Dependency3 with lazy = False, singleton=True, service = True

overriding bean parameters:

appScope.registerBean(Bean(Dependency1, singleton = False), Dependency2, Dependency3)

in this case Dependency1 will be non-singleton bean

Services

All beans can have functions, annotated with @PostConstruct and/or PreDestroy decorators, these functions will be called automatically: @PostConstruct marked functions will be called for each bean after

appScope.runServices()

and @PreDestroy marked will be called after

appScope.stopServices()

Inject scope

Each bean can inject the scope itself (avoiding circular dependencies)

from scopeton.decorators import Inject
class Dependency():
    @Inject()
    def __init__(self, scope: Scope):
        self

Non constructor injection

Scopeton can inject beans not only in constructor injection:

from scopeton.decorators import Inject
class Dependency():
    @Inject()
    def some_method(self, dependency: DependencyBean):
        self

In this case some_method will be called during bean creation and DependencyBean will be injected as a parameter