Add multibind class provider

Author: Letsch22

.gitignore

@@ -10,3 +10,4 @@ coverage.xml
 /dist/
 /injector.egg-info/
 /.coverage
+venv/

injector/__init__.py

@@ -369,6 +369,17 @@ def __repr__(self) -> str:
         return '%s(%r)' % (type(self).__name__, self._providers)
 
 
+@private
+class ClassListProvider(Provider[List[T]]):
+    """Provides a list of instances from a given class."""
+
+    def __init__(self, cls: Type[T]) -> None:
+        self._cls = cls
+
+    def get(self, injector: 'Injector') -> List[T]:
+        return [injector.create_object(self._cls)]
+
+
 class MultiBindProvider(ListOfProviders[List[T]]):
     """Used by :meth:`Binder.multibind` to flatten results of providers that
     return sequences."""
@@ -377,6 +388,15 @@ def get(self, injector: 'Injector') -> List[T]:
         return [i for provider in self._providers for i in provider.get(injector)]
 
 
+class MultiBindClassProvider(MultiBindProvider):
+    """A provider for a list of classes from a list of class instances"""
+
+    def __init__(self, classes: List[Type[T]]) -> None:
+        super().__init__()
+        for cls in classes:
+            self.append(ClassListProvider(cls))
+
+
 class MapBindProvider(ListOfProviders[Dict[str, T]]):
     """A provider for map bindings."""
 

injector_test.py

@@ -26,6 +26,7 @@
     Binder,
     CallError,
     Injector,
+    MultiBindClassProvider,
     Scope,
     InstanceProvider,
     ClassProvider,
@@ -473,6 +474,14 @@ def provide_description(self, age: int, weight: float) -> str:
 
 
 def test_multibind():
+    class A:
+        def print(self) -> str:
+            return 'A'
+
+    class B(A):
+        def print(self) -> str:
+            return 'B'
+
     # First let's have some explicit multibindings
     def configure(binder):
         binder.multibind(List[str], to=['not a name'])
@@ -483,6 +492,8 @@ def configure(binder):
         # To see that NewTypes are treated distinctly
         binder.multibind(Names, to=['Bob'])
         binder.multibind(Passwords, to={'Bob': 'password1'})
+        # To see that MultiBindClassProvider works for lists of types
+        binder.multibind(List[A], to=MultiBindClassProvider([A, B]))
 
     # Then @multiprovider-decorated Module methods
     class CustomModule(Module):
@@ -517,6 +528,8 @@ def provide_passwords(self) -> Passwords:
     assert injector.get(Dict[str, int]) == {'weight': 12, 'height': 33}
     assert injector.get(Names) == ['Bob', 'Alice', 'Clarice']
     assert injector.get(Passwords) == {'Bob': 'password1', 'Alice': 'aojrioeg3', 'Clarice': 'clarice30'}
+    assert injector.get(List[A])[0].print() == 'A'
+    assert injector.get(List[A])[1].print() == 'B'
 
 
 def test_regular_bind_and_provider_dont_work_with_multibind():