Allow aliasing a hook and calling it by it's alias

pre_commit/clientlib.py

@@ -29,6 +29,20 @@ def _make_argparser(filenames_help):
     return parser
 
 
+class OptionalAlias(object):
+
+    def check(self, dct):
+        if 'alias' in dct:
+            cfgv.check_string(dct['alias'])
+
+    def apply_default(self, dct):
+        if 'alias' not in dct:
+            dct['alias'] = dct['id']
+
+    def remove_default(self, dct):
+        pass
+
+
 MANIFEST_HOOK_DICT = cfgv.Map(
     'Hook', 'id',
 
@@ -36,6 +50,7 @@ MANIFEST_HOOK_DICT = cfgv.Map(
     cfgv.Required('name', cfgv.check_string),
     cfgv.Required('entry', cfgv.check_string),
     cfgv.Required('language', cfgv.check_one_of(all_languages)),
+    cfgv.OptionalNoDefault('alias', cfgv.check_string),
 
     cfgv.Optional(
         'files', cfgv.check_and(cfgv.check_string, cfgv.check_regex), '',
@@ -125,6 +140,7 @@ CONFIG_HOOK_DICT = cfgv.Map(
     'Hook', 'id',
 
     cfgv.Required('id', cfgv.check_string),
+    OptionalAlias(),
 
     # All keys in manifest hook dict are valid in a config hook dict, but
     # are optional.
@@ -133,7 +149,7 @@ CONFIG_HOOK_DICT = cfgv.Map(
     *[
         cfgv.OptionalNoDefault(item.key, item.check_fn)
         for item in MANIFEST_HOOK_DICT.items
-        if item.key != 'id'
+        if item.key not in ('id', 'alias')
     ]
 )
 CONFIG_REPO_DICT = cfgv.Map(