Issue #15944: memoryview: Allow arbitrary formats when casting to bytes. · pythoncapi/cpython@0c51595 · GitHub
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Issue python#15944: memoryview: Allow arbitrary formats when casting to bytes.
Original patch by Martin Panter.
1 parent 917c2c3 commit 0c51595

5 files changed

Lines changed: 57 additions & 11 deletions

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‎Doc/library/stdtypes.rst‎

Lines changed: 4 additions & 1 deletion

‎Lib/test/test_buffer.py‎

Lines changed: 27 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -2559,8 +2559,7 @@ def test_memoryview_cast_invalid(self):
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ex = ndarray(sitems, shape=[1], format=sfmt)
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msrc = memoryview(ex)
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for dfmt, _, _ in iter_format(1):
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if (not is_memoryview_format(sfmt) or
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not is_memoryview_format(dfmt)):
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if not is_memoryview_format(dfmt):
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self.assertRaises(ValueError, msrc.cast, dfmt,
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[32//dsize])
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else:
@@ -2773,6 +2772,32 @@ def test_memoryview_cast_1D_ND(self):
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ndim=ndim, shape=shape, strides=strides,
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lst=lst, cast=True)
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if ctypes:
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# format: "T{>l:x:>d:y:}"
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class BEPoint(ctypes.BigEndianStructure):
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_fields_ = [("x", ctypes.c_long), ("y", ctypes.c_double)]
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point = BEPoint(100, 200.1)
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m1 = memoryview(point)
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m2 = m1.cast('B')
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self.assertEqual(m2.obj, point)
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self.assertEqual(m2.itemsize, 1)
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self.assertEqual(m2.readonly, 0)
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self.assertEqual(m2.ndim, 1)
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self.assertEqual(m2.shape, (m2.nbytes,))
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self.assertEqual(m2.strides, (1,))
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self.assertEqual(m2.suboffsets, ())
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x = ctypes.c_double(1.2)
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m1 = memoryview(x)
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m2 = m1.cast('c')
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self.assertEqual(m2.obj, x)
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self.assertEqual(m2.itemsize, 1)
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self.assertEqual(m2.readonly, 0)
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self.assertEqual(m2.ndim, 1)
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self.assertEqual(m2.shape, (m2.nbytes,))
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self.assertEqual(m2.strides, (1,))
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self.assertEqual(m2.suboffsets, ())
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def test_memoryview_tolist(self):
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# Most tolist() tests are in self.verify() etc.

‎Lib/test/test_memoryview.py‎

Lines changed: 21 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -492,5 +492,26 @@ class ArrayMemorySliceSliceTest(unittest.TestCase,
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pass
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495+
class OtherTest(unittest.TestCase):
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def test_ctypes_cast(self):
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# Issue 15944: Allow all source formats when casting to bytes.
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ctypes = test.support.import_module("ctypes")
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p6 = bytes(ctypes.c_double(0.6))
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d = ctypes.c_double()
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m = memoryview(d).cast("B")
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m[:2] = p6[:2]
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m[2:] = p6[2:]
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self.assertEqual(d.value, 0.6)
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for format in "Bbc":
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with self.subTest(format):
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d = ctypes.c_double()
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m = memoryview(d).cast(format)
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m[:2] = memoryview(p6).cast(format)[:2]
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m[2:] = memoryview(p6).cast(format)[2:]
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self.assertEqual(d.value, 0.6)
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515+
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if __name__ == "__main__":
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unittest.main()

‎Misc/NEWS‎

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -98,6 +98,9 @@ Core and Builtins
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- Issue #24687: Plug refleak on SyntaxError in function parameters
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annotations.
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- Issue #15944: memoryview: Allow arbitrary formats when casting to bytes.
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Patch by Martin Panter.
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Library
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-------
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‎Objects/memoryobject.c‎

Lines changed: 2 additions & 8 deletions

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