add shortcut to get component

essence/__init__.py

@@ -1,4 +1,4 @@
 from .world import World, NoSuchComponentError, DuplicateComponentError
-from .entity import Entity
+from .entity import Entity, UnregisteredComponentError
 from .component import Component
 from .system import System

essence/entity.py

@@ -66,6 +66,14 @@ def destroy(self, *args, **kargs):
         """
         return self.world.destroy_entitiy(self, *args, **kargs)
 
+    def __getattr__(self, name):
+        try:
+            component_type = self.world.registry[name]
+        except KeyError:
+            raise UnregisteredComponentError()
+        else:
+            return self.get(component_type)
+
     def __eq__(self, other):
         return self.world is other.world and self.uid == other.uid
 
@@ -78,4 +86,7 @@ def __repr__(self):
     def __lt__(self, other):
         return self.uid < other.uid
 
+class UnregisteredComponentError(KeyError):
+    pass
+
 

essence/world.py

@@ -13,6 +13,7 @@ def __init__(self):
         self._entities = []
         self._entities_by_component = {}
         self.systems = []
+        self.registry = {}
 
     def _get_relation(self, component_type):
         try:
@@ -138,10 +139,11 @@ def update(self, *args, **kwargs):
         for system in self.systems:
             system.update(self, *args, **kwargs)
 
+    def register(self, name, component_type):
+        self.registry[name] = component_type
+
 class DuplicateComponentError(Exception):
     pass
 
 class NoSuchComponentError(KeyError):
     pass
-
-

tests/test_entity.py

@@ -36,4 +36,3 @@ def test_equilivent_entities_are_equal():
     assert alice != bob
     assert mars_alice != mars_bob
 
-

tests/test_shortcuts.py

@@ -1,6 +1,8 @@
-from essence import World, System, Component
+from essence import World, System, Component, UnregisteredComponentError
 from fixtures import world
 
+import pytest
+
 def xtest_there_is_a_global_world_instance():
     from essence.base import world
 
@@ -18,4 +20,14 @@ def test_entity_shorthand(world):
     entity.destroy()
     assert entity not in world.entities
 
+def test_shortcut_for_registered_components(world):
+    world.register('component', Component)
+    c = Component()
+    e = world.create_entity()
+    e.add(c)
+    assert e.component == c
 
+def test_fails_on_unregistered_components(world):
+    e = world.create_entity()
+    with pytest.raises(UnregisteredComponentError):
+        e.component