bpo-29741: Update some methods in the _pyio module to also accept integer types.…

bpo-29741: Update some methods in the _pyio module to also accept integer types. Patch by Oren Milman. (#560)

Lib/_pyio.py

@@ -504,8 +504,13 @@ class IOBase(metaclass=abc.ABCMeta):
                 return 1
         if size is None:
             size = -1
-        elif not isinstance(size, int):
-            raise TypeError("size must be an integer")
+        else:
+            try:
+                size_index = size.__index__
+            except AttributeError:
+                raise TypeError(f"{size!r} is not an integer")
+            else:
+                size = size_index()
         res = bytearray()
         while size < 0 or len(res) < size:
             b = self.read(nreadahead())
@@ -868,6 +873,13 @@ class BytesIO(BufferedIOBase):
             raise ValueError("read from closed file")
         if size is None:
             size = -1
+        else:
+            try:
+                size_index = size.__index__
+            except AttributeError:
+                raise TypeError(f"{size!r} is not an integer")
+            else:
+                size = size_index()
         if size < 0:
             size = len(self._buffer)
         if len(self._buffer) <= self._pos:
@@ -905,9 +917,11 @@ class BytesIO(BufferedIOBase):
         if self.closed:
             raise ValueError("seek on closed file")
         try:
-            pos.__index__
-        except AttributeError as err:
-            raise TypeError("an integer is required") from err
+            pos_index = pos.__index__
+        except AttributeError:
+            raise TypeError(f"{pos!r} is not an integer")
+        else:
+            pos = pos_index()
         if whence == 0:
             if pos < 0:
                 raise ValueError("negative seek position %r" % (pos,))
@@ -932,9 +946,11 @@ class BytesIO(BufferedIOBase):
             pos = self._pos
         else:
             try:
-                pos.__index__
-            except AttributeError as err:
-                raise TypeError("an integer is required") from err
+                pos_index = pos.__index__
+            except AttributeError:
+                raise TypeError(f"{pos!r} is not an integer")
+            else:
+                pos = pos_index()
             if pos < 0:
                 raise ValueError("negative truncate position %r" % (pos,))
         del self._buffer[pos:]
@@ -2378,11 +2394,14 @@ class TextIOWrapper(TextIOBase):
         self._checkReadable()
         if size is None:
             size = -1
+        else:
+            try:
+                size_index = size.__index__
+            except AttributeError:
+                raise TypeError(f"{size!r} is not an integer")
+            else:
+                size = size_index()
         decoder = self._decoder or self._get_decoder()
-        try:
-            size.__index__
-        except AttributeError as err:
-            raise TypeError("an integer is required") from err
         if size < 0:
             # Read everything.
             result = (self._get_decoded_chars() +
@@ -2413,8 +2432,13 @@ class TextIOWrapper(TextIOBase):
             raise ValueError("read from closed file")
         if size is None:
             size = -1
-        elif not isinstance(size, int):
-            raise TypeError("size must be an integer")
+        else:
+            try:
+                size_index = size.__index__
+            except AttributeError:
+                raise TypeError(f"{size!r} is not an integer")
+            else:
+                size = size_index()
 
         # Grab all the decoded text (we will rewind any extra bits later).
         line = self._get_decoded_chars()

Lib/test/test_memoryio.py

@@ -11,6 +11,13 @@ import _pyio as pyio
 import pickle
 import sys
 
+class IntLike:
+    def __init__(self, num):
+        self._num = num
+    def __index__(self):
+        return self._num
+    __int__ = __index__
+
 class MemorySeekTestMixin:
 
     def testInit(self):
@@ -116,7 +123,10 @@ class MemoryTestMixin:
         memio = self.ioclass(buf)
 
         self.assertRaises(ValueError, memio.truncate, -1)
+        self.assertRaises(ValueError, memio.truncate, IntLike(-1))
         memio.seek(6)
+        self.assertEqual(memio.truncate(IntLike(8)), 8)
+        self.assertEqual(memio.getvalue(), buf[:8])
         self.assertEqual(memio.truncate(), 6)
         self.assertEqual(memio.getvalue(), buf[:6])
         self.assertEqual(memio.truncate(4), 4)
@@ -131,6 +141,7 @@ class MemoryTestMixin:
         self.assertRaises(TypeError, memio.truncate, '0')
         memio.close()
         self.assertRaises(ValueError, memio.truncate, 0)
+        self.assertRaises(ValueError, memio.truncate, IntLike(0))
 
     def test_init(self):
         buf = self.buftype("1234567890")
@@ -154,12 +165,19 @@ class MemoryTestMixin:
         self.assertEqual(memio.read(900), buf[5:])
         self.assertEqual(memio.read(), self.EOF)
         memio.seek(0)
+        self.assertEqual(memio.read(IntLike(0)), self.EOF)
+        self.assertEqual(memio.read(IntLike(1)), buf[:1])
+        self.assertEqual(memio.read(IntLike(4)), buf[1:5])
+        self.assertEqual(memio.read(IntLike(900)), buf[5:])
+        memio.seek(0)
         self.assertEqual(memio.read(), buf)
         self.assertEqual(memio.read(), self.EOF)
         self.assertEqual(memio.tell(), 10)
         memio.seek(0)
         self.assertEqual(memio.read(-1), buf)
         memio.seek(0)
+        self.assertEqual(memio.read(IntLike(-1)), buf)
+        memio.seek(0)
         self.assertEqual(type(memio.read()), type(buf))
         memio.seek(100)
         self.assertEqual(type(memio.read()), type(buf))
@@ -169,6 +187,8 @@ class MemoryTestMixin:
         memio.seek(len(buf) + 1)
         self.assertEqual(memio.read(1), self.EOF)
         memio.seek(len(buf) + 1)
+        self.assertEqual(memio.read(IntLike(1)), self.EOF)
+        memio.seek(len(buf) + 1)
         self.assertEqual(memio.read(), self.EOF)
         memio.close()
         self.assertRaises(ValueError, memio.read)
@@ -178,6 +198,7 @@ class MemoryTestMixin:
         memio = self.ioclass(buf * 2)
 
         self.assertEqual(memio.readline(0), self.EOF)
+        self.assertEqual(memio.readline(IntLike(0)), self.EOF)
         self.assertEqual(memio.readline(), buf)
         self.assertEqual(memio.readline(), buf)
         self.assertEqual(memio.readline(), self.EOF)
@@ -186,9 +207,16 @@ class MemoryTestMixin:
         self.assertEqual(memio.readline(5), buf[5:10])
         self.assertEqual(memio.readline(5), buf[10:15])
         memio.seek(0)
+        self.assertEqual(memio.readline(IntLike(5)), buf[:5])
+        self.assertEqual(memio.readline(IntLike(5)), buf[5:10])
+        self.assertEqual(memio.readline(IntLike(5)), buf[10:15])
+        memio.seek(0)
         self.assertEqual(memio.readline(-1), buf)
         memio.seek(0)
+        self.assertEqual(memio.readline(IntLike(-1)), buf)
+        memio.seek(0)
         self.assertEqual(memio.readline(0), self.EOF)
+        self.assertEqual(memio.readline(IntLike(0)), self.EOF)
         # Issue #24989: Buffer overread
         memio.seek(len(buf) * 2 + 1)
         self.assertEqual(memio.readline(), self.EOF)

Misc/NEWS.d/next/Library/2017-08-23-00-31-32.bpo-29741.EBn_DM.rst

+Update some methods in the _pyio module to also accept integer types. Patch
+by Oren Milman.