From 3e887222aa758ac5a3fb61c8e77e909372462d00 Mon Sep 17 00:00:00 2001
From: Berker Peksag <berker.peksag@gmail.com>
Date: Wed, 2 Jul 2014 08:37:22 +0300
Subject: Issue #5800: headers parameter of wsgiref.headers.Headers is now
 optional.

Patch by Pablo Torres Navarrete and SilentGhost.
---
 Doc/library/wsgiref.rst  | 9 +++++++--
 Doc/whatsnew/3.5.rst     | 6 ++++++
 Lib/test/test_wsgiref.py | 6 +++---
 Lib/wsgiref/headers.py   | 4 ++--
 Misc/NEWS                | 3 +++
 5 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/Doc/library/wsgiref.rst b/Doc/library/wsgiref.rst
index 1cef2e9..2238140 100644
--- a/Doc/library/wsgiref.rst
+++ b/Doc/library/wsgiref.rst
@@ -184,10 +184,11 @@ This module provides a single class, :class:`Headers`, for convenient
 manipulation of WSGI response headers using a mapping-like interface.
 
 
-.. class:: Headers(headers)
+.. class:: Headers([headers])
 
    Create a mapping-like object wrapping *headers*, which must be a list of header
-   name/value tuples as described in :pep:`3333`.
+   name/value tuples as described in :pep:`3333`. The default value of *headers* is
+   an empty list.
 
    :class:`Headers` objects support typical mapping operations including
    :meth:`__getitem__`, :meth:`get`, :meth:`__setitem__`, :meth:`setdefault`,
@@ -251,6 +252,10 @@ manipulation of WSGI response headers using a mapping-like interface.
          Content-Disposition: attachment; filename="bud.gif"
 
 
+   .. versionchanged:: 3.5
+      *headers* parameter is optional.
+
+
 :mod:`wsgiref.simple_server` -- a simple WSGI HTTP server
 ---------------------------------------------------------
 
diff --git a/Doc/whatsnew/3.5.rst b/Doc/whatsnew/3.5.rst
index 9fff48c..0842143 100644
--- a/Doc/whatsnew/3.5.rst
+++ b/Doc/whatsnew/3.5.rst
@@ -230,6 +230,12 @@ socket
   :meth:`socket.socket.send`.
   (contributed by Giampaolo Rodola' in :issue:`17552`)
 
+wsgiref
+-------
+
+* *headers* parameter of :class:`wsgiref.headers.Headers` is now optional.
+  (Contributed by Pablo Torres Navarrete and SilentGhost in :issue:`5800`.)
+
 xmlrpc
 ------
 
diff --git a/Lib/test/test_wsgiref.py b/Lib/test/test_wsgiref.py
index 901f3c9..190f3ba 100644
--- a/Lib/test/test_wsgiref.py
+++ b/Lib/test/test_wsgiref.py
@@ -338,6 +338,7 @@ class HeaderTests(TestCase):
 
     def testMappingInterface(self):
         test = [('x','y')]
+        self.assertEqual(len(Headers()), 0)
         self.assertEqual(len(Headers([])),0)
         self.assertEqual(len(Headers(test[:])),1)
         self.assertEqual(Headers(test[:]).keys(), ['x'])
@@ -345,7 +346,7 @@ class HeaderTests(TestCase):
         self.assertEqual(Headers(test[:]).items(), test)
         self.assertIsNot(Headers(test).items(), test)  # must be copy!
 
-        h=Headers([])
+        h = Headers()
         del h['foo']   # should not raise an error
 
         h['Foo'] = 'bar'
@@ -370,9 +371,8 @@ class HeaderTests(TestCase):
     def testRequireList(self):
         self.assertRaises(TypeError, Headers, "foo")
 
-
     def testExtras(self):
-        h = Headers([])
+        h = Headers()
         self.assertEqual(str(h),'\r\n')
 
         h.add_header('foo','bar',baz="spam")
diff --git a/Lib/wsgiref/headers.py b/Lib/wsgiref/headers.py
index d939628..7931bc7 100644
--- a/Lib/wsgiref/headers.py
+++ b/Lib/wsgiref/headers.py
@@ -26,10 +26,10 @@ def _formatparam(param, value=None, quote=1):
 
 
 class Headers:
-
     """Manage a collection of HTTP response headers"""
 
-    def __init__(self,headers):
+    def __init__(self, headers=None):
+        headers = headers if headers is not None else []
         if type(headers) is not list:
             raise TypeError("Headers must be a list of name/value tuples")
         self._headers = headers
diff --git a/Misc/NEWS b/Misc/NEWS
index ad521b5..0428775 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -103,6 +103,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #5800: headers parameter of wsgiref.headers.Headers is now optional.
+  Initial patch by Pablo Torres Navarrete and SilentGhost.
+
 - Issue #21781: ssl.RAND_add() now supports strings longer than 2 GB.
 
 - Issue #21679: Prevent extraneous fstat() calls during open().  Patch by
-- 
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