diff --git a/Doc/library/pdb.rst b/Doc/library/pdb.rst index 5bc48a6d5f77fd..8a386aa77368f2 100644 --- a/Doc/library/pdb.rst +++ b/Doc/library/pdb.rst @@ -263,6 +263,21 @@ the commands; the input is split at the first ``;;`` pair, even if it is in the middle of a quoted string. A workaround for strings with double semicolons is to use implicit string concatenation ``';'';'`` or ``";"";"``. +To set a temporary global variable, use a *convenience variable*. A *convenience +variable* is a variable whose name starts with ``$``. For example, ``$foo = 1`` +sets a global variable ``$foo`` which you can use in the debugger session. The +*convenience variables* are cleared when the program resumes execution so it's +less likely to interfere with your program compared to using normal variables +like ``foo = 1``. + +There are three preset *convenience variables*: + +* ``$_frame``: the current frame you are debugging +* ``$_retval``: the return value if the frame is returning +* ``$_exception``: the exception if the frame is raising an exception + +.. versionadded:: 3.12 + .. index:: pair: .pdbrc; file triple: debugger; configuration; file diff --git a/Doc/whatsnew/3.12.rst b/Doc/whatsnew/3.12.rst index f9406653e625b5..3bfd8fcbf3a4f3 100644 --- a/Doc/whatsnew/3.12.rst +++ b/Doc/whatsnew/3.12.rst @@ -356,6 +356,14 @@ os.path * Add :func:`os.path.splitroot` to split a path into a triad ``(drive, root, tail)``. (Contributed by Barney Gale in :gh:`101000`.) +pdb +--- + +* Add convenience variables to hold values temporarily for debug session + and provide quick access to values like the current frame or the return + value. + (Contributed by Tian Gao in :gh:`103693`.) + shutil ------ diff --git a/Lib/pdb.py b/Lib/pdb.py index a3553b345a8dd3..e7d885ce5179ed 100755 --- a/Lib/pdb.py +++ b/Lib/pdb.py @@ -270,6 +270,8 @@ def forget(self): self.lineno = None self.stack = [] self.curindex = 0 + if hasattr(self, 'curframe') and self.curframe: + self.curframe.f_globals.pop('__pdb_convenience_variables', None) self.curframe = None self.tb_lineno.clear() @@ -288,6 +290,7 @@ def setup(self, f, tb): # locals whenever the .f_locals accessor is called, so we # cache it here to ensure that modifications are not overwritten. self.curframe_locals = self.curframe.f_locals + self.set_convenience_variable(self.curframe, '_frame', self.curframe) return self.execRcLines() # Can be executed earlier than 'setup' if desired @@ -359,6 +362,7 @@ def user_return(self, frame, return_value): if self._wait_for_mainpyfile: return frame.f_locals['__return__'] = return_value + self.set_convenience_variable(frame, '_retval', return_value) self.message('--Return--') self.interaction(frame, None) @@ -369,6 +373,7 @@ def user_exception(self, frame, exc_info): return exc_type, exc_value, exc_traceback = exc_info frame.f_locals['__exception__'] = exc_type, exc_value + self.set_convenience_variable(frame, '_exception', exc_value) # An 'Internal StopIteration' exception is an exception debug event # issued by the interpreter when handling a subgenerator run with @@ -394,6 +399,7 @@ def _cmdloop(self): self.message('--KeyboardInterrupt--') # Called before loop, handles display expressions + # Set up convenience variable containers def preloop(self): displaying = self.displaying.get(self.curframe) if displaying: @@ -477,6 +483,9 @@ def precmd(self, line): next = line[marker+2:].lstrip() self.cmdqueue.append(next) line = line[:marker].rstrip() + + # Replace all the convenience variables + line = re.sub(r'\$([a-zA-Z_][a-zA-Z0-9_]*)', r'__pdb_convenience_variables["\1"]', line) return line def onecmd(self, line): @@ -527,6 +536,13 @@ def message(self, msg): def error(self, msg): print('***', msg, file=self.stdout) + # convenience variables + + def set_convenience_variable(self, frame, name, value): + if '__pdb_convenience_variables' not in frame.f_globals: + frame.f_globals['__pdb_convenience_variables'] = {} + frame.f_globals['__pdb_convenience_variables'][name] = value + # Generic completion functions. Individual complete_foo methods can be # assigned below to one of these functions. @@ -1018,6 +1034,7 @@ def _select_frame(self, number): self.curindex = number self.curframe = self.stack[self.curindex][0] self.curframe_locals = self.curframe.f_locals + self.set_convenience_variable(self.curframe, '_frame', self.curframe) self.print_stack_entry(self.stack[self.curindex]) self.lineno = None diff --git a/Lib/test/test_pdb.py b/Lib/test/test_pdb.py index 94b441720f258c..8a171c3ecd8831 100644 --- a/Lib/test/test_pdb.py +++ b/Lib/test/test_pdb.py @@ -746,6 +746,84 @@ def test_pdb_where_command(): (Pdb) continue """ +def test_convenience_variables(): + """Test convenience variables + + >>> def util_function(): + ... import pdb; pdb.Pdb(nosigint=True, readrc=False).set_trace() + ... try: + ... raise Exception('test') + ... except: + ... pass + ... return 1 + + >>> def test_function(): + ... util_function() + + >>> with PdbTestInput([ # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE + ... '$_frame.f_lineno', # Check frame convenience variable + ... '$a = 10', # Set a convenience variable + ... '$a', # Print its value + ... 'p $a + 2', # Do some calculation + ... 'u', # Switch frame + ... '$_frame.f_lineno', # Make sure the frame changed + ... '$a', # Make sure the value persists + ... 'd', # Go back to the original frame + ... 'next', + ... '$a', # The value should be gone + ... 'next', + ... '$_exception', # Check exception convenience variable + ... 'next', + ... '$_exception', # Exception should be gone + ... 'return', + ... '$_retval', # Check return convenience variable + ... 'continue', + ... ]): + ... test_function() + > (3)util_function() + -> try: + (Pdb) $_frame.f_lineno + 3 + (Pdb) $a = 10 + (Pdb) $a + 10 + (Pdb) p $a + 2 + 12 + (Pdb) u + > (2)test_function() + -> util_function() + (Pdb) $_frame.f_lineno + 2 + (Pdb) $a + 10 + (Pdb) d + > (3)util_function() + -> try: + (Pdb) next + > (4)util_function() + -> raise Exception('test') + (Pdb) $a + *** KeyError: 'a' + (Pdb) next + Exception: test + > (4)util_function() + -> raise Exception('test') + (Pdb) $_exception + Exception('test') + (Pdb) next + > (5)util_function() + -> except: + (Pdb) $_exception + *** KeyError: '_exception' + (Pdb) return + --Return-- + > (7)util_function()->1 + -> return 1 + (Pdb) $_retval + 1 + (Pdb) continue + """ + def test_post_mortem(): """Test post mortem traceback debugging. diff --git a/Misc/NEWS.d/next/Library/2023-04-22-21-34-13.gh-issue-103693.SBtuLQ.rst b/Misc/NEWS.d/next/Library/2023-04-22-21-34-13.gh-issue-103693.SBtuLQ.rst new file mode 100644 index 00000000000000..52c68bfc9ceea4 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2023-04-22-21-34-13.gh-issue-103693.SBtuLQ.rst @@ -0,0 +1 @@ +Add convenience variable feature to :mod:`pdb` pFad - Phonifier reborn

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