help command temporarily redirects sys.stdout and sys.stderr to self.stdout for argparse commands

In order to make "help" behave more consistently for decorated and undecorated commands, argparse output is temporarily redirected to self.stdout.  So doing "help history" is similar to "help load".

However, when using the "-h" with argparse commands without using the "help" command, the output from argparse isn't redirected to self.stdout.  Fixing this would be rather difficult and would essentially involve creating a pyparsing rule to detect it at the parser level.

1 files changed, 23 insertions, 11 deletions

diff --git a/cmd2.py b/cmd2.py
index aee6f958..c397bb7c 100755
--- a/cmd2.py
+++ b/cmd2.py
@@ -92,8 +92,12 @@ except ImportError:
 # BrokenPipeError is only in Python 3. Use IOError for Python 2.
 if six.PY3:
     BROKEN_PIPE_ERROR = BrokenPipeError
+
+    # redirect_stdout and redirect_stderr weren't added to contextlib until Python 3.4
+    from contextlib import redirect_stdout, redirect_stderr
 else:
     BROKEN_PIPE_ERROR = IOError
+    from contextlib2 import redirect_stdout, redirect_stderr
 
 # On some systems, pyperclip will import gtk for its clipboard functionality.
 # The following code is a workaround for gtk interfering with printing from a background
@@ -668,6 +672,9 @@ class Cmd(cmd.Cmd):
         # Used when piping command output to a shell command
         self.pipe_proc = None
 
+        # Used by complete() for readline tab completion
+        self.completion_matches = []
+
     # -----  Methods related to presenting output to the user -----
 
     @property
@@ -771,13 +778,14 @@ class Cmd(cmd.Cmd):
 
         return cmd_completion
 
+    # noinspection PyUnusedLocal
     def complete_subcommand(self, text, line, begidx, endidx):
         """Readline tab-completion method for completing argparse sub-command names."""
-        cmd, args, foo = self.parseline(line)
+        command, args, foo = self.parseline(line)
         arglist = args.split()
 
-        if len(arglist) <= 1 and cmd + ' ' + args == line:
-            funcname = self._func_named(cmd)
+        if len(arglist) <= 1 and command + ' ' + args == line:
+            funcname = self._func_named(command)
             if funcname:
                 # Check to see if this function was decorated with an argparse ArgumentParser
                 func = getattr(self, funcname)
@@ -799,7 +807,7 @@ class Cmd(cmd.Cmd):
         return []
 
     def complete(self, text, state):
-        """Override of cmd method which returns the next possible completion for 'text'.
+        """Override of command method which returns the next possible completion for 'text'.
 
         If a command has not been entered, then complete against command list.
         Otherwise try to call complete_<command> to get list of completions.
@@ -819,17 +827,17 @@ class Cmd(cmd.Cmd):
             stripped = len(origline) - len(line)
             begidx = readline.get_begidx() - stripped
             endidx = readline.get_endidx() - stripped
-            if begidx>0:
-                cmd, args, foo = self.parseline(line)
-                if cmd == '':
+            if begidx > 0:
+                command, args, foo = self.parseline(line)
+                if command == '':
                     compfunc = self.completedefault
                 else:
                     arglist = args.split()
 
                     compfunc = None
                     # If the user has entered no more than a single argument after the command name
-                    if len(arglist) <= 1 and cmd + ' ' + args == line:
-                        funcname = self._func_named(cmd)
+                    if len(arglist) <= 1 and command + ' ' + args == line:
+                        funcname = self._func_named(command)
                         if funcname:
                             # Check to see if this function was decorated with an argparse ArgumentParser
                             func = getattr(self, funcname)
@@ -842,7 +850,7 @@ class Cmd(cmd.Cmd):
                     if compfunc is None:
                         # This command either doesn't have sub-commands or the user is past the point of entering one
                         try:
-                            compfunc = getattr(self, 'complete_' + cmd)
+                            compfunc = getattr(self, 'complete_' + command)
                         except AttributeError:
                             compfunc = self.completedefault
             else:
@@ -1319,7 +1327,11 @@ class Cmd(cmd.Cmd):
                     # Function has an argparser, so get help based on all the arguments in case there are sub-commands
                     new_arglist = arglist[1:]
                     new_arglist.append('-h')
-                    func(new_arglist)
+
+                    # Temporarily redirect all argparse output to both sys.stdout and sys.stderr to self.stdout
+                    with redirect_stdout(self.stdout):
+                        with redirect_stderr(self.stdout):
+                            func(new_arglist)
                 else:
                     # No special behavior needed, delegate to cmd base class do_help()
                     cmd.Cmd.do_help(self, funcname[3:])