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Commit 0fc58c6

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gaogaotiantiangaogaotiantian
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gh-103693: Add convenience variable feature to pdb (#103694)
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‎Doc/library/pdb.rst

Copy file name to clipboardExpand all lines: Doc/library/pdb.rst
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@@ -263,6 +263,21 @@ the commands; the input is split at the first ``;;`` pair, even if it is in the
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middle of a quoted string. A workaround for strings with double semicolons
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is to use implicit string concatenation ``';'';'`` or ``";"";"``.
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To set a temporary global variable, use a *convenience variable*. A *convenience
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variable* is a variable whose name starts with ``$``. For example, ``$foo = 1``
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sets a global variable ``$foo`` which you can use in the debugger session. The
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*convenience variables* are cleared when the program resumes execution so it's
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less likely to interfere with your program compared to using normal variables
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like ``foo = 1``.
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There are three preset *convenience variables*:
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* ``$_frame``: the current frame you are debugging
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* ``$_retval``: the return value if the frame is returning
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* ``$_exception``: the exception if the frame is raising an exception
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.. versionadded:: 3.12
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.. index::
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pair: .pdbrc; file
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triple: debugger; configuration; file

‎Doc/whatsnew/3.12.rst

Copy file name to clipboardExpand all lines: Doc/whatsnew/3.12.rst
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@@ -408,6 +408,14 @@ os.path
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* Add :func:`os.path.splitroot` to split a path into a triad
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``(drive, root, tail)``. (Contributed by Barney Gale in :gh:`101000`.)
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pdb
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---
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* Add convenience variables to hold values temporarily for debug session
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and provide quick access to values like the current frame or the return
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value.
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(Contributed by Tian Gao in :gh:`103693`.)
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411419
shutil
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------
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‎Lib/pdb.py

Copy file name to clipboardExpand all lines: Lib/pdb.py
+17Lines changed: 17 additions & 0 deletions
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@@ -270,6 +270,8 @@ def forget(self):
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self.lineno = None
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self.stack = []
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self.curindex = 0
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if hasattr(self, 'curframe') and self.curframe:
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self.curframe.f_globals.pop('__pdb_convenience_variables', None)
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self.curframe = None
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self.tb_lineno.clear()
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@@ -288,6 +290,7 @@ def setup(self, f, tb):
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# locals whenever the .f_locals accessor is called, so we
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# cache it here to ensure that modifications are not overwritten.
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self.curframe_locals = self.curframe.f_locals
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self.set_convenience_variable(self.curframe, '_frame', self.curframe)
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return self.execRcLines()
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# Can be executed earlier than 'setup' if desired
@@ -359,6 +362,7 @@ def user_return(self, frame, return_value):
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if self._wait_for_mainpyfile:
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return
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frame.f_locals['__return__'] = return_value
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self.set_convenience_variable(frame, '_retval', return_value)
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self.message('--Return--')
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self.interaction(frame, None)
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@@ -369,6 +373,7 @@ def user_exception(self, frame, exc_info):
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return
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exc_type, exc_value, exc_traceback = exc_info
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frame.f_locals['__exception__'] = exc_type, exc_value
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self.set_convenience_variable(frame, '_exception', exc_value)
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# An 'Internal StopIteration' exception is an exception debug event
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# issued by the interpreter when handling a subgenerator run with
@@ -394,6 +399,7 @@ def _cmdloop(self):
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self.message('--KeyboardInterrupt--')
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# Called before loop, handles display expressions
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# Set up convenience variable containers
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def preloop(self):
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displaying = self.displaying.get(self.curframe)
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if displaying:
@@ -477,6 +483,9 @@ def precmd(self, line):
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next = line[marker+2:].lstrip()
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self.cmdqueue.append(next)
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line = line[:marker].rstrip()
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# Replace all the convenience variables
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line = re.sub(r'\$([a-zA-Z_][a-zA-Z0-9_]*)', r'__pdb_convenience_variables["\1"]', line)
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return line
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def onecmd(self, line):
@@ -527,6 +536,13 @@ def message(self, msg):
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def error(self, msg):
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print('***', msg, file=self.stdout)
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# convenience variables
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def set_convenience_variable(self, frame, name, value):
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if '__pdb_convenience_variables' not in frame.f_globals:
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frame.f_globals['__pdb_convenience_variables'] = {}
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frame.f_globals['__pdb_convenience_variables'][name] = value
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# Generic completion functions. Individual complete_foo methods can be
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# assigned below to one of these functions.
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@@ -1018,6 +1034,7 @@ def _select_frame(self, number):
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self.curindex = number
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self.curframe = self.stack[self.curindex][0]
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self.curframe_locals = self.curframe.f_locals
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self.set_convenience_variable(self.curframe, '_frame', self.curframe)
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self.print_stack_entry(self.stack[self.curindex])
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self.lineno = None
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‎Lib/test/test_pdb.py

Copy file name to clipboardExpand all lines: Lib/test/test_pdb.py
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@@ -746,6 +746,84 @@ def test_pdb_where_command():
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(Pdb) continue
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"""
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def test_convenience_variables():
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"""Test convenience variables
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>>> def util_function():
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... import pdb; pdb.Pdb(nosigint=True, readrc=False).set_trace()
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... try:
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... raise Exception('test')
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... except:
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... pass
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... return 1
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>>> def test_function():
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... util_function()
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>>> with PdbTestInput([ # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
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... '$_frame.f_lineno', # Check frame convenience variable
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... '$a = 10', # Set a convenience variable
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... '$a', # Print its value
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... 'p $a + 2', # Do some calculation
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... 'u', # Switch frame
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... '$_frame.f_lineno', # Make sure the frame changed
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... '$a', # Make sure the value persists
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... 'd', # Go back to the original frame
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... 'next',
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... '$a', # The value should be gone
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... 'next',
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... '$_exception', # Check exception convenience variable
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... 'next',
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... '$_exception', # Exception should be gone
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... 'return',
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... '$_retval', # Check return convenience variable
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... 'continue',
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... ]):
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... test_function()
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> <doctest test.test_pdb.test_convenience_variables[0]>(3)util_function()
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-> try:
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(Pdb) $_frame.f_lineno
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3
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(Pdb) $a = 10
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(Pdb) $a
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10
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(Pdb) p $a + 2
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12
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(Pdb) u
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> <doctest test.test_pdb.test_convenience_variables[1]>(2)test_function()
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-> util_function()
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(Pdb) $_frame.f_lineno
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2
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(Pdb) $a
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10
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(Pdb) d
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> <doctest test.test_pdb.test_convenience_variables[0]>(3)util_function()
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-> try:
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(Pdb) next
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> <doctest test.test_pdb.test_convenience_variables[0]>(4)util_function()
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-> raise Exception('test')
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(Pdb) $a
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*** KeyError: 'a'
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(Pdb) next
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Exception: test
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> <doctest test.test_pdb.test_convenience_variables[0]>(4)util_function()
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-> raise Exception('test')
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(Pdb) $_exception
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Exception('test')
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(Pdb) next
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> <doctest test.test_pdb.test_convenience_variables[0]>(5)util_function()
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-> except:
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(Pdb) $_exception
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*** KeyError: '_exception'
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(Pdb) return
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--Return--
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> <doctest test.test_pdb.test_convenience_variables[0]>(7)util_function()->1
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-> return 1
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(Pdb) $_retval
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1
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(Pdb) continue
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"""
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def test_post_mortem():
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"""Test post mortem traceback debugging.
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‎Misc/NEWS.d/next/Library/2023-04-22-21-34-13.gh-issue-103693.SBtuLQ.rst

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Add convenience variable feature to :mod:`pdb`

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