Merge pull request #2 from runemalm/feature/constructor-args

Feature/constructor args

README.md

@@ -60,6 +60,13 @@ third_container = DependencyContainer.get_instance(name="third_container")
 dependency_container.register_transient(SomeInterface, SomeClass)
 dependency_container.register_scoped(AnotherInterface, AnotherClass)
 dependency_container.register_singleton(ThirdInterface, ThirdClass)
+
+# Registering dependencies with constructor arguments
+dependency_container.register_transient(
+    SomeInterface,
+    SomeClass,
+    constructor_args={"arg1": value1, "arg2": value2}
+)
 ```
 
 ### Resolving dependencies using the container
@@ -139,6 +146,21 @@ To contribute, create a pull request on the develop branch following the [git fl
 
 ## Release Notes
 
+### [1.0.0-alpha.4](https://github.com/runemalm/py-dependency-injection/releases/tag/v1.0.0-alpha.4) (2024-03-02)
+
+- **New Feature**: Support for constructor arguments in dependency registration: In this release, we introduce the ability to specify constructor arguments when registering dependencies with the container. This feature provides more flexibility when configuring dependencies, allowing users to customize the instantiation of classes during registration.
+
+    **Usage Example:**
+    ```python
+    # Registering a dependency with constructor arguments
+    dependency_container.register_transient(
+        SomeInterface, SomeClass,
+        constructor_args={"arg1": value1, "arg2": value2}
+    )
+    ```
+
+    Users can now pass specific arguments to be used during the instantiation of the dependency. This is particularly useful when a class requires dynamic or configuration-dependent parameters.
+
 ### [1.0.0-alpha.3](https://github.com/runemalm/py-dependency-injection/releases/tag/v1.0.0-alpha.3) (2024-03-02)
 
 - **Breaking Change**: Restriction on `@inject` Decorator: Starting from this version, the `@inject` decorator can now only be used on static class methods and class methods. This change is introduced due to potential pitfalls associated with resolving and injecting dependencies directly into class instance methods using the dependency container.

docs/conf.py

@@ -34,7 +34,7 @@
 version = '1.0'
 
 # The full version, including alpha/beta/rc tags
-release = '1.0.0-alpha.3'
+release = '1.0.0-alpha.4'
 
 
 # -- General configuration ---------------------------------------------------

docs/versionhistory.rst

@@ -2,6 +2,22 @@
 Version history
 ###############
 
+**1.0.0-alpha.4 (2024-03-02)**
+
+- **New Feature**: Support for constructor arguments in dependency registration: In this release, we introduce the ability to specify constructor arguments when registering dependencies with the container. This feature provides more flexibility when configuring dependencies, allowing users to customize the instantiation of classes during registration.
+
+    **Usage Example:**::
+    
+        # Registering a dependency with constructor arguments
+        dependency_container.register_transient(
+            SomeInterface, SomeClass,
+            constructor_args={"arg1": value1, "arg2": value2}
+        )
+
+    Users can now pass specific arguments to be used during the instantiation of the dependency. This is particularly useful when a class requires dynamic or configuration-dependent parameters.
+
+`View release on GitHub <https://github.com/runemalm/py-dependency-injection/releases/tag/v1.0.0-alpha.4>`_
+
 **1.0.0-alpha.3 (2024-03-02)**
 
 - **Breaking Change**: Restriction on `@inject` Decorator: Starting from this version, the `@inject` decorator can now only be used on static class methods and class methods. This change is introduced due to potential pitfalls associated with resolving and injecting dependencies directly into class instance methods using the dependency container.

setup.py

@@ -6,7 +6,7 @@
 
 setup(
     name='py-dependency-injection',
-    version='1.0.0-alpha.3',
+    version='1.0.0-alpha.4',
     author='David Runemalm, 2024',
     author_email='david.runemalm@gmail.com',
     description=

src/dependency_injection/container.py

@@ -1,4 +1,5 @@
 import inspect
+from typing import Any, Dict, Type
 
 from dependency_injection.registration import Registration
 from dependency_injection.scope import DEFAULT_SCOPE_NAME, Scope
@@ -25,20 +26,20 @@ def get_instance(cls, name=None):
 
         return cls._instances[(cls, name)]
 
-    def register_transient(self, interface, class_):
+    def register_transient(self, interface, class_, constructor_args=None):
         if interface in self._registrations:
             raise ValueError(f"Dependency {interface} is already registered.")
-        self._registrations[interface] = Registration(interface, class_, Scope.TRANSIENT)
+        self._registrations[interface] = Registration(interface, class_, Scope.TRANSIENT, constructor_args)
 
-    def register_scoped(self, interface, class_):
+    def register_scoped(self, interface, class_, constructor_args=None):
         if interface in self._registrations:
             raise ValueError(f"Dependency {interface} is already registered.")
-        self._registrations[interface] = Registration(interface, class_, Scope.SCOPED)
+        self._registrations[interface] = Registration(interface, class_, Scope.SCOPED, constructor_args)
 
-    def register_singleton(self, interface, class_):
+    def register_singleton(self, interface, class_, constructor_args=None):
         if interface in self._registrations:
             raise ValueError(f"Dependency {interface} is already registered.")
-        self._registrations[interface] = Registration(interface, class_, Scope.SINGLETON)
+        self._registrations[interface] = Registration(interface, class_, Scope.SINGLETON, constructor_args)
 
     def resolve(self, interface, scope_name=DEFAULT_SCOPE_NAME):
         if scope_name not in self._scoped_instances:
@@ -50,24 +51,62 @@ def resolve(self, interface, scope_name=DEFAULT_SCOPE_NAME):
         registration = self._registrations[interface]
         dependency_scope = registration.scope
         dependency_class = registration.class_
+        constructor_args = registration.constructor_args
+
+        self._validate_constructor_args(constructor_args=constructor_args, class_=dependency_class)
 
         if dependency_scope == Scope.TRANSIENT:
-            return self._inject_dependencies(dependency_class)
+            return self._inject_dependencies(
+                class_=dependency_class,
+                constructor_args=constructor_args
+            )
         elif dependency_scope == Scope.SCOPED:
             if interface not in self._scoped_instances[scope_name]:
                 self._scoped_instances[scope_name][interface] = (
                     self._inject_dependencies(
                         class_=dependency_class,
-                        scope_name=scope_name,))
+                        scope_name=scope_name,
+                        constructor_args=constructor_args,
+                    ))
             return self._scoped_instances[scope_name][interface]
         elif dependency_scope == Scope.SINGLETON:
             if interface not in self._singleton_instances:
-                self._singleton_instances[interface] = self._inject_dependencies(dependency_class)
+                self._singleton_instances[interface] = (
+                    self._inject_dependencies(
+                        class_=dependency_class,
+                        constructor_args=constructor_args
+                    )
+                )
             return self._singleton_instances[interface]
 
         raise ValueError(f"Invalid dependency scope: {dependency_scope}")
 
-    def _inject_dependencies(self, class_, scope_name=None):
+    def _validate_constructor_args(self, constructor_args: Dict[str, Any], class_: Type) -> None:
+        class_constructor = inspect.signature(class_.__init__).parameters
+
+        # Check if any required parameter is missing
+        missing_params = [param for param in class_constructor.keys() if
+                          param not in ["self", "cls", "args", "kwargs"] and
+                          param not in constructor_args]
+        if missing_params:
+            raise ValueError(
+                f"Missing required constructor arguments: "
+                f"{', '.join(missing_params)} for class '{class_.__name__}'.")
+
+        for arg_name, arg_value in constructor_args.items():
+            if arg_name not in class_constructor:
+                raise ValueError(
+                    f"Invalid constructor argument '{arg_name}' for class '{class_.__name__}'. "
+                    f"The class does not have a constructor parameter with this name.")
+
+            expected_type = class_constructor[arg_name].annotation
+            if expected_type != inspect.Parameter.empty:
+                if not isinstance(arg_value, expected_type):
+                    raise TypeError(
+                        f"Constructor argument '{arg_name}' has an incompatible type. "
+                        f"Expected type: {expected_type}, provided type: {type(arg_value)}.")
+
+    def _inject_dependencies(self, class_, scope_name=None, constructor_args=None):
         constructor = inspect.signature(class_.__init__)
         params = constructor.parameters
 
@@ -82,6 +121,10 @@ def _inject_dependencies(self, class_, scope_name=None):
                     # **kwargs parameter
                     pass
                 else:
-                    dependencies[param_name] = self.resolve(param_info.annotation, scope_name=scope_name)
+                    # Check if constructor_args has an argument with the same name
+                    if constructor_args and param_name in constructor_args:
+                        dependencies[param_name] = constructor_args[param_name]
+                    else:
+                        dependencies[param_name] = self.resolve(param_info.annotation, scope_name=scope_name)
 
         return class_(**dependencies)

src/dependency_injection/registration.py

@@ -1,9 +1,12 @@
+from typing import Any, Dict
+
 from dependency_injection.scope import Scope
 
 
 class Registration():
 
-    def __init__(self, interface, class_, scope: Scope):
+    def __init__(self, interface, class_, scope: Scope, constructor_args: Dict[str, Any] = None):
         self.interface = interface
         self.class_ = class_
         self.scope = scope
+        self.constructor_args = constructor_args or {}

tests/unit_test/container/register/test_register_scoped.py

@@ -1,9 +1,7 @@
 import pytest
 
 from dependency_injection.container import DependencyContainer
-from unit_test.car import Car
 from unit_test.unit_test_case import UnitTestCase
-from unit_test.vehicle import Vehicle
 
 
 class TestRegisterScoped(UnitTestCase):
@@ -12,6 +10,12 @@ def test_register_scoped_succeeds_when_not_previously_registered(
         self,
     ):
         # arrange
+        class Vehicle:
+            pass
+
+        class Car(Vehicle):
+            pass
+
         dependency_container = DependencyContainer.get_instance()
         interface = Vehicle
         dependency_class = Car
@@ -26,6 +30,12 @@ def test_register_scoped_fails_when_already_registered(
         self,
     ):
         # arrange
+        class Vehicle:
+            pass
+
+        class Car(Vehicle):
+            pass
+
         dependency_container = DependencyContainer.get_instance()
         interface = Vehicle
         dependency_class = Car

tests/unit_test/container/register/test_register_singleton.py

@@ -1,9 +1,7 @@
 import pytest
 
 from dependency_injection.container import DependencyContainer
-from unit_test.car import Car
 from unit_test.unit_test_case import UnitTestCase
-from unit_test.vehicle import Vehicle
 
 
 class TestRegisterSingleton(UnitTestCase):
@@ -12,6 +10,12 @@ def test_register_singleton_succeeds_when_not_previously_registered(
         self,
     ):
         # arrange
+        class Vehicle:
+            pass
+
+        class Car(Vehicle):
+            pass
+
         dependency_container = DependencyContainer.get_instance()
         interface = Vehicle
         dependency_class = Car
@@ -26,6 +30,12 @@ def test_register_singleton_fails_when_already_registered(
         self,
     ):
         # arrange
+        class Vehicle:
+            pass
+
+        class Car(Vehicle):
+            pass
+
         dependency_container = DependencyContainer.get_instance()
         interface = Vehicle
         dependency_class = Car

tests/unit_test/container/register/test_register_transient.py

@@ -1,9 +1,7 @@
 import pytest
 
 from dependency_injection.container import DependencyContainer
-from unit_test.car import Car
 from unit_test.unit_test_case import UnitTestCase
-from unit_test.vehicle import Vehicle
 
 
 class TestRegisterTransient(UnitTestCase):
@@ -12,20 +10,31 @@ def test_register_transient_succeeds_when_not_previously_registered(
         self,
     ):
         # arrange
+        class Vehicle:
+            pass
+
+        class Car(Vehicle):
+            pass
+
         dependency_container = DependencyContainer.get_instance()
         interface = Vehicle
         dependency_class = Car
 
         # act
         dependency_container.register_transient(interface, dependency_class)
 
-        # assert
-        # (no exception thrown)
+        # assert (no exception thrown)
 
     def test_register_transient_fails_when_already_registered(
         self,
     ):
         # arrange
+        class Vehicle:
+            pass
+
+        class Car(Vehicle):
+            pass
+
         dependency_container = DependencyContainer.get_instance()
         interface = Vehicle
         dependency_class = Car

tests/unit_test/container/register/test_register_with_args.py

@@ -0,0 +1,22 @@
+from dependency_injection.container import DependencyContainer
+from unit_test.unit_test_case import UnitTestCase
+
+
+class TestRegisterWithArgs(UnitTestCase):
+
+    def test_register_with_constructor_args(
+        self,
+    ):
+        # arrange
+        class Vehicle:
+            pass
+
+        class Car(Vehicle):
+            pass
+
+        dependency_container = DependencyContainer.get_instance()
+        interface = Vehicle
+        dependency_class = Car
+
+        # act + assert (no exception)
+        dependency_container.register_transient(interface, dependency_class, constructor_args={"color": "red", "mileage": 3800})

tests/unit_test/container/resolve/test_resolve_scoped.py

@@ -1,7 +1,5 @@
 from dependency_injection.container import DependencyContainer
-from unit_test.car import Car
 from unit_test.unit_test_case import UnitTestCase
-from unit_test.vehicle import Vehicle
 
 
 class TestResolveScoped(UnitTestCase):
@@ -10,6 +8,12 @@ def test_resolve_scoped_in_same_scope_returns_same_instance(
         self,
     ):
         # arrange
+        class Vehicle:
+            pass
+
+        class Car(Vehicle):
+            pass
+
         dependency_container = DependencyContainer.get_instance()
         interface = Vehicle
         dependency_class = Car
@@ -26,6 +30,12 @@ def test_resolve_scoped_in_different_scopes_returns_different_instances(
         self,
     ):
         # arrange
+        class Vehicle:
+            pass
+
+        class Car(Vehicle):
+            pass
+
         dependency_container = DependencyContainer.get_instance()
         interface = Vehicle
         dependency_class = Car