[Python-checkins] bpo-30721: Show correct syntax hint in Py3 when using Py2 redirection syntax (#2345)
Serhiy Storchaka
webhook-mailer at python.org
Fri Aug 18 06:37:39 EDT 2017
https://github.com/python/cpython/commit/5e2eb35bbed3e84079165e576cdb50ef36e13493
commit: 5e2eb35bbed3e84079165e576cdb50ef36e13493
branch: master
author: Sanyam Khurana <sanyam at sanyamkhurana.com>
committer: Serhiy Storchaka <storchaka at gmail.com>
date: 2017-08-18T13:37:36+03:00
summary:
bpo-30721: Show correct syntax hint in Py3 when using Py2 redirection syntax (#2345)
files:
A Misc/NEWS.d/next/Core and Builtins/2017-08-18-15-15-20.bpo-30721.Hmc56z.rst
M Lib/test/test_print.py
M Objects/abstract.c
diff --git a/Lib/test/test_print.py b/Lib/test/test_print.py
index 03f13b4edfc..80993279b8d 100644
--- a/Lib/test/test_print.py
+++ b/Lib/test/test_print.py
@@ -1,4 +1,5 @@
import unittest
+import sys
from io import StringIO
from test import support
@@ -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()
diff --git a/Misc/NEWS.d/next/Core and Builtins/2017-08-18-15-15-20.bpo-30721.Hmc56z.rst b/Misc/NEWS.d/next/Core and Builtins/2017-08-18-15-15-20.bpo-30721.Hmc56z.rst
new file mode 100644
index 00000000000..da553d654ec
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2017-08-18-15-15-20.bpo-30721.Hmc56z.rst
@@ -0,0 +1,2 @@
+``print`` now shows correct usage hint for using Python 2 redirection
+syntax. Patch by Sanyam Khurana.
diff --git a/Objects/abstract.c b/Objects/abstract.c
index cb026c0df5d..abd97953bd9 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -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;
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