Converting various classes to namedtuples

appengine/findit/lib/gitiles/change_log.py

Index: appengine/findit/lib/gitiles/change_log.py
diff --git a/appengine/findit/lib/gitiles/change_log.py b/appengine/findit/lib/gitiles/change_log.py
index b14c93f03b1f6da63bcf21d49bfc353a394d8b8a..3f1686dfe2956c5e3f25445dddd7be55b3c2037e 100644
--- a/appengine/findit/lib/gitiles/change_log.py
+++ b/appengine/findit/lib/gitiles/change_log.py
@@ -2,13 +2,45 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-# TODO(http://crbug.com/661822): convert this into a namedtuple.
-class FileChangeInfo(object):
+from collections import namedtuple
+
+from lib.gitiles.diff import ChangeType
+
+# TODO(wrengr): it'd be better to have a class hierarchy here, so we can
+# avoid playing around with None, and so the change_type can be stored
+# once (in the class itself; rather than once per instance).
+# TODO(http://crbug/644476): better name for this class; i.e., without
+# the extraneous \"Info\" at the very least.
+# TODO(http://crbug.com/659346): coverage tests for the smart constructors.
+class FileChangeInfo(namedtuple('FileChangeInfo',
+    ['change_type', 'old_path', 'new_path'])):
   """Represents a file change (add/delete/modify/rename/copy/etc)."""
-  def __init__(self, change_type, old_path, new_path):
-    self.change_type = change_type
-    self.old_path = old_path
-    self.new_path = new_path
+  __slots__ = ()
+
+  @classmethod
+  def Modify(cls, path): # pragma: no cover
+    return cls(ChangeType.MODIFY, path, path)
+
+  @classmethod
+  def Add(cls, path): # pragma: no cover
+    # Stay the same as gitile.
+    return cls(ChangeType.ADD, None, path)
+
+  @classmethod
+  def Delete(cls, path): # pragma: no cover
+    return cls(ChangeType.DELETE, path, None)
+
+  @classmethod
+  def Rename(cls, old_path, new_path): # pragma: no cover
+    return cls(ChangeType.RENAME, old_path, new_path)
+
+  @classmethod
+  def Copy(cls, old_path, new_path): # pragma: no cover
+    return cls(ChangeType.COPY, old_path, new_path)
+
+  @classmethod
+  def FromDict(cls, info):
+    return cls(info['change_type'].lower(), info['old_path'], info['new_path'])
 
   def ToDict(self):
     return {
@@ -17,33 +49,24 @@ class FileChangeInfo(object):
         'new_path': self.new_path
     }
 
-  @staticmethod
-  def FromDict(info):
-    return FileChangeInfo(
-        info['change_type'], info['old_path'], info['new_path'])
-
 
-# TODO(http://crbug.com/661822): convert this into a namedtuple.
-class ChangeLog(object):
+class ChangeLog(namedtuple('ChangeLog',
+    ['author_name', 'author_email', 'author_time', 'committer_name',
+     'committer_email', 'committer_time', 'revision', 'commit_position',
+     'message', 'touched_files', 'commit_url', 'code_review_url',
+     'reverted_revision'])):
   """Represents the change log of a revision."""
+  __slots__ = ()
 
-  def __init__(self, author_name, author_email, author_time, committer_name,
-               committer_email, committer_time, revision, commit_position,
-               message, touched_files, commit_url, code_review_url=None,
-               reverted_revision=None):
-    self.author_name = author_name
-    self.author_email = author_email
-    self.author_time = author_time
-    self.committer_name = committer_name
-    self.committer_email = committer_email
-    self.committer_time = committer_time
-    self.revision = revision
-    self.commit_position = commit_position
-    self.touched_files = touched_files
-    self.message = message
-    self.commit_url = commit_url
-    self.code_review_url = code_review_url
-    self.reverted_revision = reverted_revision
+  def __new__(cls, author_name, author_email, author_time, committer_name,
+              committer_email, committer_time, revision, commit_position,
+              message, touched_files, commit_url, code_review_url=None,
+              reverted_revision=None):
+    return super(cls, ChangeLog).__new__(cls,
+        author_name, author_email, author_time, committer_name,
+        committer_email, committer_time, revision, commit_position,
+        message, touched_files, commit_url, code_review_url, 
+        reverted_revision)
 
   def ToDict(self):
     """Returns the change log as a JSON object."""
@@ -71,7 +94,12 @@ class ChangeLog(object):
     """Returns a ChangeLog instance represented by the given JSON info."""
     touched_files = []
     for touched_file_info in info['touched_files']:
-      touched_files.append(FileChangeInfo.FromDict(touched_file_info))
+      if isinstance(touched_file_info, dict):
+        touched_file_info = FileChangeInfo.FromDict(touched_file_info)
+      if not isinstance(touched_file_info, FileChangeInfo): # pragma: no cover
+        raise TypeError("expected FileChangeInfo but got %s"
+            % touched_file_info.__class__.__name__)
+      touched_files.append(touched_file_info)
 
     return ChangeLog(
         info['author_name'], info['author_email'], info['author_time'],