Simple Inject

中文 README

Simple Inject is a lightweight Python dependency injection library. It provides an easy-to-use interface for managing dependencies across different namespaces and scopes.

Features

• Simple and intuitive dependency injection API
• Supports multiple namespaces to isolate dependencies
• Implements scoped dependencies using context managers or decorators
• Supports nested scopes for fine-grained control
• Supports automatic dependency injection through parameters
• Easy integration with existing projects
• Minimal overhead and dependencies

Installation

You can install Simple Inject using pip:

pip install py-simple-inject

Quick Start

Basic Usage

Here is a simple example demonstrating basic dependency injection and scope management:

from simple_inject import provide, inject, create_scope

# Provide a dependency
provide('config', {'debug': True})

# Inject a dependency
config = inject('config')
print(config['debug'])  # Output: True

Using Namespaces

from simple_inject import provide, inject, create_scope

provide('key', 'value1', namespace='ns1')
provide('key', 'value2', namespace='ns2')

print(inject('key', namespace='ns1'))  # Output: value1
print(inject('key', namespace='ns2'))  # Output: value2

Using Scopes

provide('config', {'debug': True})

# Use scopes to manage dependencies
with create_scope():
    provide('config', {'debug': False})
    config = inject('config')
    print(config['debug'])  # Output: False

# Outside the scope, the original value is preserved
config = inject('config')
print(config['debug'])  # Output: True

Scopes can also be used with the scoped decorator:

@scoped()
def scoped_function():
    provide('key', 'scoped_value')
    return inject('key')

provide('key', 'outer_value')
print(inject('key'))  # Output: outer_value
print(scoped_function())  # Output: scoped_value
print(inject('key'))  # Output: outer_value

Nested Scopes

Scoped scopes can be nested, and dependencies in inner scopes will override those in outer scopes.

provide('key', 'outer')

with create_scope():
    provide('key', 'inner')
    print(inject('key'))  # Output: inner

    with create_scope():
        provide('key', 'innermost')
        print(inject('key'))  # Output: innermost

    print(inject('key'))  # Output: inner

print(inject('key'))  # Output: outer

Automatic Injection via Function Parameters

Simple Inject also supports automatic injection via function parameters. The following example demonstrates how to use this advanced feature:

from simple_inject import provide, inject, create_scope, auto_inject, Inject

class Engine:
    def start(self):
        print("Engine started")

# Provide a dependency
provide('engine', Engine())

# Manually inject a dependency
engine = inject('engine')
engine.start()  # Output: Engine started

# Use automatic injection
@auto_inject()
def drive(car: str, engine: Engine = Inject('engine')):
    print(f"Driving {car}")
    engine.start()

drive("Tesla")  # Output: Driving Tesla and Engine started

# Use scopes to manage dependencies
with create_scope():
    provide('engine', Engine())  # Provide a new Engine instance
    drive("BMW")  # Output: Driving BMW and Engine started

# Outside the scope, the original value is preserved
drive("Toyota")  # Output: Driving Toyota and Engine started

API Reference

provide(key: str, value: Any, namespace: str = 'default')

Provides a dependency in the current context.

inject(key: str, namespace: str = 'default') -> Any

Injects a dependency from the current context.

create_scope()

Creates a new dependency scope. Used with the with statement.

scoped()

Decorator to create a new dependency scope for a function.

auto_inject()

Decorator to automatically inject parameters marked with Inject.

Inject(key: str, namespace: str = 'default')

Class to mark a parameter for automatic injection.

purge(namespace: Optional[str] = None)

Clears dependencies, either for a specific namespace or for all namespaces.

Contributing

Contributions are welcome! Feel free to submit a Pull Request.

License

This project is licensed under the MIT License - see the LICENSE file for details.