Add sketch

src/dependency_injector/providers.pyx

@@ -324,6 +324,10 @@ cdef class Object(Provider):
         """
         return self.__str__()
 
+    @property
+    def provided(self):
+        return ProvidedAttributes(self)
+
     cpdef object _provide(self, tuple args, dict kwargs):
         """Return provided instance.
 
@@ -769,6 +773,10 @@ cdef class Callable(Provider):
         """Return wrapped callable."""
         return self.__provides
 
+    @property
+    def provided(self):
+        return ProvidedAttributes(self)
+
     @property
     def args(self):
         """Return positional argument injections."""
@@ -1599,6 +1607,10 @@ cdef class Factory(Provider):
         """Return provided type."""
         return self.__instantiator.provides
 
+    @property
+    def provided(self):
+        return ProvidedAttributes(self)
+
     @property
     def args(self):
         """Return positional argument injections."""
@@ -1932,6 +1944,10 @@ cdef class BaseSingleton(Provider):
         """Return provided type."""
         return self.__instantiator.cls
 
+    @property
+    def provided(self):
+        return ProvidedAttributes(self)
+
     @property
     def args(self):
         """Return positional argument injections."""
@@ -2360,6 +2376,10 @@ cdef class List(Provider):
         """
         return represent_provider(provider=self, provides=list(self.args))
 
+    @property
+    def provided(self):
+        return ProvidedAttributes(self)
+
     @property
     def args(self):
         """Return positional argument injections."""
@@ -2537,6 +2557,10 @@ cdef class Selector(Provider):
             address=hex(id(self)),
         )
 
+    @property
+    def provided(self):
+        return ProvidedAttributes(self)
+
     @property
     def providers(self):
         """Return providers."""
@@ -2555,6 +2579,118 @@ cdef class Selector(Provider):
         return self.__providers[selector_value](*args, **kwargs)
 
 
+class ProvidedAttributes(Provider):
+
+    def __init__(self, provider):
+        self._provider = provider
+        super().__init__()
+
+    def __repr__(self):
+        return f'ProvidedAttributes({self._provider})'
+
+    def __deepcopy__(self, memo=None):
+        return self.__class__(deepcopy(self._provider, memo))
+
+    def __getattr__(self, item):
+        return AttributeGetter(self, item)
+
+    def __getitem__(self, item):
+        return ItemGetter(self, item)
+
+    def call(self, *args, **kwargs):
+        return MethodCaller(self, *args, **kwargs)
+
+    def _provide(self, args, kwargs):
+        return self._provider(*args, **kwargs)
+
+
+class AttributeGetter(Provider):
+
+    def __init__(self, provider, attribute):
+        self._provider = provider
+        self._attribute = attribute
+        super().__init__()
+
+    def __repr__(self):
+        return f'AttributeGetter({self._attribute})'
+
+    def __deepcopy__(self, memo=None):
+        return self.__class__(deepcopy(self._provider, memo), self._attribute)
+
+    def __getattr__(self, item):
+        return AttributeGetter(self, item)
+
+    def __getitem__(self, item):
+        return ItemGetter(self, item)
+
+    def call(self, *args, **kwargs):
+        return MethodCaller(self, *args, **kwargs)
+
+    def _provide(self, args, kwargs):
+        provided = self._provider(*args, **kwargs)
+        return getattr(provided, self._attribute)
+
+
+class ItemGetter(Provider):
+
+    def __init__(self, provider, item):
+        self._provider = provider
+        self._item = item
+        super().__init__()
+
+    def __repr__(self):
+        return f'ItemGetter({self._item})'
+
+    def __deepcopy__(self, memo=None):
+        return self.__class__(deepcopy(self._provider, memo), self._item)
+
+    def __getattr__(self, item):
+        return AttributeGetter(self, item)
+
+    def __getitem__(self, item):
+        return ItemGetter(self, item)
+
+    def call(self, *args, **kwargs):
+        return MethodCaller(self, *args, **kwargs)
+
+    def _provide(self, args, kwargs):
+        provided = self._provider(*args, **kwargs)
+        return provided[self._item]
+
+
+class MethodCaller(Provider):
+
+    def __init__(self, provider, *args, **kwargs):
+        self._provider = provider
+        self._args = args
+        self._kwargs = kwargs
+        super().__init__()
+
+    def __repr__(self):
+        return f'MethodCaller({self._provider})'
+
+    def __deepcopy__(self, memo=None):
+        return self.__class__(
+            deepcopy(self._provider, memo),
+            *deepcopy(self._args, memo),
+            **deepcopy(self._kwargs, memo),
+        )
+
+    def __getattr__(self, item):
+        return AttributeGetter(self, item)
+
+    def __getitem__(self, item):
+        return ItemGetter(self, item)
+
+    def call(self, *args, **kwargs):
+        return MethodCaller(self, *args, **kwargs)
+
+    def _provide(self, args, kwargs):
+        provided = self._provider(*args, **kwargs)
+        # TODO: add proper handling of injections
+        return provided(*self._args, **self._kwargs)
+
+
 cdef class Injection(object):
     """Abstract injection class."""