[Python-checkins] bpo-31389 Add an optional `header` argument to pdb.set_trace() (#3438)

Fri Sep 22 12:29:45 EDT 2017

https://github.com/python/cpython/commit/35425d638c0eeb8377620e016f47df3ae08d7061
commit: 35425d638c0eeb8377620e016f47df3ae08d7061
branch: master
author: Barry Warsaw <barry at python.org>
committer: GitHub <noreply at github.com>
date: 2017年09月22日T12:29:42-04:00
summary:
bpo-31389 Add an optional `header` argument to pdb.set_trace() (#3438)
* Give pdb.set_trace() an optional `header` argument
* What's new.
* Give pdb.set_trace() an optional `header` argument
* What's new.
files:
A Misc/NEWS.d/next/Library/2017-09-07-15-31-47.bpo-31389.jNFYqB.rst
M Doc/library/pdb.rst
M Doc/whatsnew/3.7.rst
M Lib/pdb.py
M Lib/test/test_pdb.py

diff --git a/Doc/library/pdb.rst b/Doc/library/pdb.rst
index 6225a3a1f07..c5d4181c35d 100644
--- a/Doc/library/pdb.rst
+++ b/Doc/library/pdb.rst
@@ -118,11 +118,15 @@ slightly different way:
 is entered.
 
 
-.. function:: set_trace()
+.. function:: set_trace(*, header=None)
 
- Enter the debugger at the calling stack frame. This is useful to hard-code a
- breakpoint at a given point in a program, even if the code is not otherwise
- being debugged (e.g. when an assertion fails).
+ Enter the debugger at the calling stack frame. This is useful to hard-code
+ a breakpoint at a given point in a program, even if the code is not
+ otherwise being debugged (e.g. when an assertion fails). If given,
+ ``header`` is printed to the console just before debugging begins.
+
+ .. versionadded:: 3.7
+ The keyword-only argument ``header``.
 
 
 .. function:: post_mortem(traceback=None)
diff --git a/Doc/whatsnew/3.7.rst b/Doc/whatsnew/3.7.rst
index 870ca066923..a19a2895828 100644
--- a/Doc/whatsnew/3.7.rst
+++ b/Doc/whatsnew/3.7.rst
@@ -232,6 +232,13 @@ New function :func:`os.register_at_fork` allows registering Python callbacks
 to be executed on a process fork. (Contributed by Antoine Pitrou in
 :issue:`16500`.)
 
+pdb
+---
+
+:func:`~pdb.set_trace` now takes an optional ``header`` keyword-only
+argument. If given, this is printed to the console just before debugging
+begins.
+
 string
 ------
 
diff --git a/Lib/pdb.py b/Lib/pdb.py
index 97618b0ff16..8dd4dedb220 100755
--- a/Lib/pdb.py
+++ b/Lib/pdb.py
@@ -1581,8 +1581,11 @@ def runctx(statement, globals, locals):
 def runcall(*args, **kwds):
 return Pdb().runcall(*args, **kwds)
 
-def set_trace():
- Pdb().set_trace(sys._getframe().f_back)
+def set_trace(*, header=None):
+ pdb = Pdb()
+ if header is not None:
+ pdb.message(header)
+ pdb.set_trace(sys._getframe().f_back)
 
 # Post-Mortem interface
 
diff --git a/Lib/test/test_pdb.py b/Lib/test/test_pdb.py
index 755d265d5c8..71d8203fc56 100644
--- a/Lib/test/test_pdb.py
+++ b/Lib/test/test_pdb.py
@@ -9,9 +9,12 @@
 import subprocess
 import textwrap
 
+from contextlib import ExitStack
+from io import StringIO
 from test import support
 # This little helper class is essential for testing pdb under doctest.
 from test.test_doctest import _FakeInput
+from unittest.mock import patch
 
 
 class PdbTestInput(object):
@@ -1107,6 +1110,15 @@ def test_readrc_kwarg(self):
 if save_home is not None:
 os.environ['HOME'] = save_home
 
+ def test_header(self):
+ stdout = StringIO()
+ header = 'Nobody expects... blah, blah, blah'
+ with ExitStack() as resources:
+ resources.enter_context(patch('sys.stdout', stdout))
+ resources.enter_context(patch.object(pdb.Pdb, 'set_trace'))
+ pdb.set_trace(header=header)
+ self.assertEqual(stdout.getvalue(), header + '\n')
+
 def tearDown(self):
 support.unlink(support.TESTFN)
 
diff --git a/Misc/NEWS.d/next/Library/2017-09-07-15-31-47.bpo-31389.jNFYqB.rst b/Misc/NEWS.d/next/Library/2017-09-07-15-31-47.bpo-31389.jNFYqB.rst
new file mode 100644
index 00000000000..7f459680967
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2017-09-07-15-31-47.bpo-31389.jNFYqB.rst
@@ -0,0 +1,2 @@
+``pdb.set_trace()`` now takes an optional keyword-only argument ``header``.
+If given, this is printed to the console just before debugging begins.
