Extract _get_callable_bindings into a top-level function

It's gonna be exposed as part of the public API.

Author: jstasiak

injector/__init__.py

@@ -796,26 +796,15 @@ def call_with_injection(self, callable, self_=None, args=(), kwargs={}):
         :return: Value returned by callable.
         """
 
-        def _get_callable_bindings(callable):
-            if not hasattr(callable, '__bindings__'):
-                return {}
-
-            if callable.__bindings__ == 'deferred':
-                read_and_store_bindings(callable, _infer_injected_bindings(callable))
-            noninjectables = getattr(callable, '__noninjectables__', set())
-            return {k: v for k, v in callable.__bindings__.items() if k not in noninjectables}
-
-        bindings = _get_callable_bindings(callable)
+        bindings = get_bindings(callable)
         signature = inspect.signature(callable)
         full_args = args
         if self_ is not None:
             full_args = (self_,) + full_args
         bound_arguments = signature.bind_partial(*full_args)
 
         needed = dict(
-            (k, v)
-            for (k, v) in bindings.items()
-            if k not in kwargs and k not in bound_arguments.arguments
+            (k, v) for (k, v) in bindings.items() if k not in kwargs and k not in bound_arguments.arguments
         )
 
         dependencies = self.args_to_inject(
@@ -874,6 +863,16 @@ def repr_key(k):
         return dependencies
 
 
+def get_bindings(callable):
+    if not hasattr(callable, '__bindings__'):
+        return {}
+
+    if callable.__bindings__ == 'deferred':
+        read_and_store_bindings(callable, _infer_injected_bindings(callable))
+    noninjectables = getattr(callable, '__noninjectables__', set())
+    return {k: v for k, v in callable.__bindings__.items() if k not in noninjectables}
+
+
 class _BindingNotYetAvailable(Exception):
     pass