Close #15442: Expand the list of default directories ignored by filecmp.dircmp and expose it as a module attribute

1 files changed, 7 insertions, 3 deletions

diff --git a/Lib/filecmp.py b/Lib/filecmp.py
index 5bbd0e8..014c0d0 100644
--- a/Lib/filecmp.py
+++ b/Lib/filecmp.py
@@ -13,11 +13,15 @@ import os
 import stat
 from itertools import filterfalse
 
-__all__ = ["cmp", "dircmp", "cmpfiles"]
+__all__ = ['cmp', 'dircmp', 'cmpfiles', 'DEFAULT_IGNORES']
 
 _cache = {}
 BUFSIZE = 8*1024
 
+DEFAULT_IGNORES = [
+    'RCS', 'CVS', 'tags', '.git', '.hg', '.bzr', '_darcs', '__pycache__']
+
+
 def cmp(f1, f2, shallow=True):
     """Compare two files.
 
@@ -80,7 +84,7 @@ class dircmp:
     dircmp(a, b, ignore=None, hide=None)
       A and B are directories.
       IGNORE is a list of names to ignore,
-        defaults to ['RCS', 'CVS', 'tags'].
+        defaults to DEFAULT_IGNORES.
       HIDE is a list of names to hide,
         defaults to [os.curdir, os.pardir].
 
@@ -116,7 +120,7 @@ class dircmp:
         else:
             self.hide = hide
         if ignore is None:
-            self.ignore = ['RCS', 'CVS', 'tags'] # Names ignored in comparison
+            self.ignore = DEFAULT_IGNORES
         else:
             self.ignore = ignore