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bpo-30721: Show correct syntax hint in Py3 when using Py2 redirection syntax #2345

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Merged
serhiy-storchaka merged 11 commits into from
Aug 18, 2017
Merged

bpo-30721: Show correct syntax hint in Py3 when using Py2 redirection syntax #2345

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b26d729
bpo-30721: WIP for showing hint in Py3 when using Py2 redirection syntax
CuriousLearner Jun 23, 2017
aa5cc11
bpo-30721: Address review comments
CuriousLearner Jun 23, 2017
7db3e71
bpo-30721: Address review comments
CuriousLearner Jul 31, 2017
6eaf005
bpo-30721: Address review comments
CuriousLearner Aug 7, 2017
7665115
bpo-30721: Address review comments
CuriousLearner Aug 18, 2017
da0fbab
bpo-30721: Address review comments
CuriousLearner Aug 18, 2017
c43e23c
bpo-30721: Adds NEWS entry and minor fixes
CuriousLearner Aug 18, 2017
bad1d7b
bpo-30721: Fixes rST news entry
CuriousLearner Aug 18, 2017
74eff16
bpo-30721: Reverts strncmp to strcmp
CuriousLearner Aug 18, 2017
d1a9641
bpo-30721: Removes manual entry to MISC/NEWS
CuriousLearner Aug 18, 2017
185050e
bpo-30721: Removes spaces around pointers
CuriousLearner Aug 18, 2017
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33 changes: 33 additions & 0 deletions Lib/test/test_print.py
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
import unittest
import sys
from io import StringIO

from test import support
Expand Down Expand Up @@ -155,6 +156,38 @@ def test_string_with_excessive_whitespace(self):

self.assertIn('print("Hello World", end=" ")', str(context.exception))

def test_stream_redirection_hint_for_py2_migration(self):
# Test correct hint produced for Py2 redirection syntax
with self.assertRaises(TypeError) as context:
print >> sys.stderr, "message"
self.assertIn('Did you mean "print(<message>, '
'file=<output_stream>)', str(context.exception))

# Test correct hint is produced in the case where RHS implements
# __rrshift__ but returns NotImplemented
with self.assertRaises(TypeError) as context:
print >> 42
self.assertIn('Did you mean "print(<message>, '
'file=<output_stream>)', str(context.exception))

# Test stream redirection hint is specific to print
with self.assertRaises(TypeError) as context:
max >> sys.stderr
self.assertNotIn('Did you mean ', str(context.exception))

# Test stream redirection hint is specific to rshift
with self.assertRaises(TypeError) as context:
print << sys.stderr
self.assertNotIn('Did you mean', str(context.exception))

# Ensure right operand implementing rrshift still works
class OverrideRRShift:
def __rrshift__(self, lhs):
return 42 # Force result independent of LHS

self.assertEqual(print >> OverrideRRShift(), 42)



if __name__ == "__main__":
unittest.main()
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2017-08-18-15-15-20.bpo-30721.Hmc56z.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
``print`` now shows correct usage hint for using Python 2 redirection
syntax. Patch by Sanyam Khurana.
15 changes: 15 additions & 0 deletions Objects/abstract.c
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Original file line number Diff line number Diff line change
Expand Up @@ -819,6 +819,21 @@ binary_op(PyObject *v, PyObject *w, const int op_slot, const char *op_name)
PyObject *result = binary_op1(v, w, op_slot);
if (result == Py_NotImplemented) {
Py_DECREF(result);

if (op_slot == NB_SLOT(nb_rshift) &&
PyCFunction_Check(v) &&
strcmp(((PyCFunctionObject *)v)->m_ml->ml_name, "print") == 0)
{
PyErr_Format(PyExc_TypeError,
"unsupported operand type(s) for %.100s: "
"'%.100s' and '%.100s'. Did you mean \"print(<message>, "
"file=<output_stream>)\"",
op_name,
v->ob_type->tp_name,
w->ob_type->tp_name);
return NULL;
}

return binop_type_error(v, w, op_name);
}
return result;
Expand Down