officially deprecated max_buffer_size

2 files changed, 38 insertions, 9 deletions

diff --git a/Lib/_pyio.py b/Lib/_pyio.py
index 5a7d2ca..654a69c 100644
--- a/Lib/_pyio.py
+++ b/Lib/_pyio.py
@@ -5,6 +5,7 @@ Python implementation of the io module.
 import os
 import abc
 import codecs
+import warnings
 # Import _thread instead of threading to reduce startup cost
 try:
     from _thread import allocate_lock as Lock
@@ -960,16 +961,20 @@ class BufferedWriter(_BufferedIOMixin):
 
     The constructor creates a BufferedWriter for the given writeable raw
     stream. If the buffer_size is not given, it defaults to
-    DEFAULT_BUFFER_SIZE. If max_buffer_size is omitted, it defaults to
-    twice the buffer size.
+    DEFAULT_BUFFER_SIZE.
     """
 
+    _warning_stack_offset = 2
+
     def __init__(self, raw,
                  buffer_size=DEFAULT_BUFFER_SIZE, max_buffer_size=None):
         raw._checkWritable()
         _BufferedIOMixin.__init__(self, raw)
         if buffer_size <= 0:
             raise ValueError("invalid buffer size")
+        if max_buffer_size is not None:
+            warnings.warn("max_buffer_size is deprecated", DeprecationWarning,
+                          self._warning_stack_offset)
         self.buffer_size = buffer_size
         self._write_buf = bytearray()
         self._write_lock = Lock()
@@ -1055,8 +1060,7 @@ class BufferedRWPair(BufferedIOBase):
 
     reader and writer are RawIOBase objects that are readable and
     writeable respectively. If the buffer_size is omitted it defaults to
-    DEFAULT_BUFFER_SIZE. The max_buffer_size (for the buffered writer)
-    defaults to twice the buffer size.
+    DEFAULT_BUFFER_SIZE.
     """
 
     # XXX The usefulness of this (compared to having two separate IO
@@ -1068,10 +1072,12 @@ class BufferedRWPair(BufferedIOBase):
 
         The arguments are two RawIO instances.
         """
+        if max_buffer_size is not None:
+            warnings.warn("max_buffer_size is deprecated", DeprecationWarning, 2)
         reader._checkReadable()
         writer._checkWritable()
         self.reader = BufferedReader(reader, buffer_size)
-        self.writer = BufferedWriter(writer, buffer_size, max_buffer_size)
+        self.writer = BufferedWriter(writer, buffer_size)
 
     def read(self, n=None):
         if n is None:
@@ -1117,10 +1123,11 @@ class BufferedRandom(BufferedWriter, BufferedReader):
 
     The constructor creates a reader and writer for a seekable stream,
     raw, given in the first argument. If the buffer_size is omitted it
-    defaults to DEFAULT_BUFFER_SIZE. The max_buffer_size (for the buffered
-    writer) defaults to twice the buffer size.
+    defaults to DEFAULT_BUFFER_SIZE.
     """
 
+    _warning_stack_offset = 3
+
     def __init__(self, raw,
                  buffer_size=DEFAULT_BUFFER_SIZE, max_buffer_size=None):
         raw._checkSeekable()
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index ef3fed9..1b80add 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -26,6 +26,7 @@ import array
 import threading
 import random
 import unittest
+import warnings
 import weakref
 import gc
 import abc
@@ -861,7 +862,7 @@ class BufferedWriterTest(unittest.TestCase, CommonBufferedTests):
 
     def test_write_non_blocking(self):
         raw = self.MockNonBlockWriterIO()
-        bufio = self.tp(raw, 8, 8)
+        bufio = self.tp(raw, 8)
 
         self.assertEquals(bufio.write(b"abcd"), 4)
         self.assertEquals(bufio.write(b"efghi"), 5)
@@ -979,6 +980,17 @@ class BufferedWriterTest(unittest.TestCase, CommonBufferedTests):
         self.assertRaises(IOError, bufio.tell)
         self.assertRaises(IOError, bufio.write, b"abcdef")
 
+    def test_max_buffer_size_deprecation(self):
+        with support.check_warnings() as w:
+            warnings.simplefilter("always", DeprecationWarning)
+            self.tp(self.MockRawIO(), 8, 12)
+            self.assertEqual(len(w.warnings), 1)
+            warning = w.warnings[0]
+            self.assertTrue(warning.category is DeprecationWarning)
+            self.assertEqual(str(warning.message),
+                             "max_buffer_size is deprecated")
+
+
 class CBufferedWriterTest(BufferedWriterTest):
     tp = io.BufferedWriter
 
@@ -1029,6 +1041,16 @@ class BufferedRWPairTest(unittest.TestCase):
         pair = self.tp(r, w)
         self.assertFalse(pair.closed)
 
+    def test_max_buffer_size_deprecation(self):
+        with support.check_warnings() as w:
+            warnings.simplefilter("always", DeprecationWarning)
+            self.tp(self.MockRawIO(), self.MockRawIO(), 8, 12)
+            self.assertEqual(len(w.warnings), 1)
+            warning = w.warnings[0]
+            self.assertTrue(warning.category is DeprecationWarning)
+            self.assertEqual(str(warning.message),
+                             "max_buffer_size is deprecated")
+
         # XXX More Tests
 
 class CBufferedRWPairTest(BufferedRWPairTest):
@@ -1048,7 +1070,7 @@ class BufferedRandomTest(BufferedReaderTest, BufferedWriterTest):
 
     def test_read_and_write(self):
         raw = self.MockRawIO((b"asdf", b"ghjk"))
-        rw = self.tp(raw, 8, 12)
+        rw = self.tp(raw, 8)
 
         self.assertEqual(b"as", rw.read(2))
         rw.write(b"ddd")