#1437051: allow "continue"/"next"/etc. in .pdbrc, also add pdb -c option to give these commands. This allows to run a script until an exception occurs.

Author: birkenfeld

Doc/library/pdb.rst

@@ -44,11 +44,15 @@ example::
    python3 -m pdb myscript.py
 
 When invoked as a script, pdb will automatically enter post-mortem debugging if
-the program being debugged exits abnormally. After post-mortem debugging (or
-after normal exit of the program), pdb will restart the program. Automatic
+the program being debugged exits abnormally.  After post-mortem debugging (or
+after normal exit of the program), pdb will restart the program.  Automatic
 restarting preserves pdb's state (such as breakpoints) and in most cases is more
 useful than quitting the debugger upon program's exit.
 
+.. versionadded:: 3.2
+   :file:`pdb.py` now accepts a ``-c`` option that executes commands as if given
+   in a :file:`.pdbrc` file, see :ref:`debugger-commands`.
+
 The typical usage to break into the debugger from a running program is to
 insert ::
 
@@ -202,6 +206,11 @@ prompt.  This is particularly useful for aliases.  If both files exist, the one
 in the home directory is read first and aliases defined there can be overridden
 by the local file.
 
+.. versionchanged:: 3.2
+   :file:`.pdbrc` can now contain commands that continue debugging, such as
+   :pdbcmd:`continue` or :pdbcmd:`next`.  Previously, these commands had no
+   effect.
+
 
 .. pdbcommand:: h(elp) [command]
 
@@ -388,9 +397,9 @@ by the local file.
    As an example, here are two useful aliases (especially when placed in the
    :file:`.pdbrc` file)::
 
-      #Print instance variables (usage "pi classInst")
+      # Print instance variables (usage "pi classInst")
       alias pi for k in %1.__dict__.keys(): print("%1.",k,"=",%1.__dict__[k])
-      #Print instance variables in self
+      # Print instance variables in self
       alias ps pi self
 
 .. pdbcommand:: unalias name

Lib/pdb.py

@@ -332,19 +332,26 @@ def setup(self, f, t):
         # 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.execRcLines()
+        return self.execRcLines()
 
     # Can be executed earlier than 'setup' if desired
     def execRcLines(self):
-        if self.rcLines:
-            # Make local copy because of recursion
-            rcLines = self.rcLines
-            # executed only once
-            self.rcLines = []
-            for line in rcLines:
-                line = line[:-1]
-                if len(line) > 0 and line[0] != '#':
-                    self.onecmd(line)
+        if not self.rcLines:
+            return
+        # local copy because of recursion
+        rcLines = self.rcLines
+        rcLines.reverse()
+        # execute every line only once
+        self.rcLines = []
+        while rcLines:
+            line = rcLines.pop().strip()
+            if line and line[0] != '#':
+                if self.onecmd(line):
+                    # if onecmd returns True, the command wants to exit
+                    # from the interaction, save leftover rc lines
+                    # to execute before next interaction
+                    self.rcLines += reversed(rcLines)
+                    return True
 
     # Override Bdb methods
 
@@ -367,7 +374,7 @@ def user_line(self, frame):
         if self.bp_commands(frame):
             self.interaction(frame, None)
 
-    def bp_commands(self,frame):
+    def bp_commands(self, frame):
         """Call every command that was set for the current active breakpoint
         (if there is one).
 
@@ -409,7 +416,11 @@ def user_exception(self, frame, exc_info):
     # General interaction function
 
     def interaction(self, frame, traceback):
-        self.setup(frame, traceback)
+        if self.setup(frame, traceback):
+            # no interaction desired at this time (happens if .pdbrc contains
+            # a command like "continue")
+            self.forget()
+            return
         self.print_stack_entry(self.stack[self.curindex])
         self.cmdloop()
         self.forget()
@@ -1497,17 +1508,42 @@ def help():
     import pydoc
     pydoc.pager(__doc__)
 
+_usage = """\
+usage: pdb.py [-c command] ... pyfile [arg] ...
+
+Debug the Python program given by pyfile.
+
+Initial commands are read from .pdbrc files in your home directory
+and in the current directory, if they exist.  Commands supplied with
+-c are executed after commands from .pdbrc files.
+
+To let the script run until an exception occurs, use "-c continue".
+To let the script run until a given line X in the debugged file, use
+"-c 'break X' -c continue"."""
+
 def main():
-    if not sys.argv[1:] or sys.argv[1] in ("--help", "-h"):
-        print("usage: pdb.py scriptfile [arg] ...")
+    import getopt
+
+    opts, args = getopt.getopt(sys.argv[1:], 'hc:', ['--help', '--command='])
+
+    if not args:
+        print(_usage)
         sys.exit(2)
 
-    mainpyfile =  sys.argv[1]     # Get script filename
+    commands = []
+    for opt, optarg in opts:
+        if opt in ['-h', '--help']:
+            print(_usage)
+            sys.exit()
+        elif opt in ['-c', '--command']:
+            commands.append(optarg)
+
+    mainpyfile = args[0]     # Get script filename
     if not os.path.exists(mainpyfile):
         print('Error:', mainpyfile, 'does not exist')
         sys.exit(1)
 
-    del sys.argv[0]         # Hide "pdb.py" from argument list
+    sys.argv[:] = args      # Hide "pdb.py" and pdb options from argument list
 
     # Replace pdb's dir with script's dir in front of module search path.
     sys.path[0] = os.path.dirname(mainpyfile)
@@ -1517,6 +1553,7 @@ def main():
     # changed by the user from the command line. There is a "restart" command
     # which allows explicit specification of command line arguments.
     pdb = Pdb()
+    pdb.rcLines.extend(commands)
     while True:
         try:
             pdb._runscript(mainpyfile)
@@ -1525,10 +1562,10 @@ def main():
             print("The program finished and will be restarted")
         except Restart:
             print("Restarting", mainpyfile, "with arguments:")
-            print("\t" + " ".join(sys.argv[1:]))
+            print("\t" + " ".join(args))
         except SystemExit:
             # In most cases SystemExit does not warrant a post-mortem session.
-            print("The program exited via sys.exit(). Exit status: ", end=' ')
+            print("The program exited via sys.exit(). Exit status:", end=' ')
             print(sys.exc_info()[1])
         except:
             traceback.print_exc()

Misc/NEWS

@@ -475,6 +475,10 @@ C-API
 Library
 -------
 
+- Issue #1437051: For pdb, allow "continue" and related commands in
+  .pdbrc files.  Also, add a command-line option "-c" that runs a
+  command as if given in .pdbrc.
+
 - Issue #4179: In pdb, allow "list ." as a command to return to the
   currently debugged line.