[config] Implements a "requires()" service injection decorator for functions (api may change).

bonobo/config/__init__.py

@@ -1,7 +1,7 @@
 from bonobo.config.configurables import Configurable
-from bonobo.config.options import Option, Method
+from bonobo.config.options import Method, Option
 from bonobo.config.processors import ContextProcessor
-from bonobo.config.services import Container, Service, Exclusive
+from bonobo.config.services import Container, Exclusive, Service, requires
 
 # bonobo.config public programming interface
 __all__ = [
@@ -12,4 +12,5 @@ __all__ = [
     'Method',
     'Option',
     'Service',
+    'requires',
 ]

bonobo/config/services.py

@@ -56,7 +56,11 @@ class Service(Option):
         inst.__options_values__[self.name] = validate_service_name(value)
 
     def resolve(self, inst, services):
-        return services.get(getattr(inst, self.name))
+        try:
+            name = getattr(inst, self.name)
+        except AttributeError:
+            name = self.name
+        return services.get(name)
 
 
 class Container(dict):
@@ -126,3 +130,19 @@ class Exclusive(ContextDecorator):
 
     def __exit__(self, *exc):
         self.get_lock().release()
+
+
+def requires(*service_names):
+    def decorate(mixed):
+        try:
+            options = mixed.__options__
+        except AttributeError:
+            mixed.__options__ = options = {}
+
+        for service_name in service_names:
+            service = Service(service_name)
+            service.name = service_name
+            options[service_name] = service
+        return mixed
+
+    return decorate