diff options
| -rwxr-xr-x | cmd2.py | 59 | ||||
| -rwxr-xr-x | examples/paged_output.py | 29 |
2 files changed, 87 insertions, 1 deletions
@@ -1133,6 +1133,9 @@ class Cmd(cmd.Cmd): # Used by complete() for readline tab completion self.completion_matches = [] + # Used to keep track of whether we are redirecting or piping output + self.redirecting = False + # ----- Methods related to presenting output to the user ----- @property @@ -1154,7 +1157,7 @@ class Cmd(cmd.Cmd): # Make sure settable parameters are sorted alphabetically by key self.settable = collections.OrderedDict(sorted(self.settable.items(), key=lambda t: t[0])) - def poutput(self, msg, end='\n'): + def poutput(self, msg, end=os.linesep): """Convenient shortcut for self.stdout.write(); by default adds newline to end if not already present. Also handles BrokenPipeError exceptions for when a commands's output has been piped to another process and @@ -1207,6 +1210,55 @@ class Cmd(cmd.Cmd): else: sys.stderr.write("{}\n".format(msg)) + def ppaged(self, msg, end=os.linesep): + """Print output using a pager if it would go off screen and stdout isn't currently being redirected. + + Never uses a pager inside of a script (Python or text) or when output is being redirected or piped. + + :param msg: str - message to print to current stdout - anything convertible to a str with '{}'.format() is OK + :param end: str - string appended after the end of the message if not already present, default a newline + """ + if msg is not None and msg != '': + try: + msg_str = '{}'.format(msg) + if not msg_str.endswith(end): + msg_str += end + + # Don't attempt to use a pager that can block if redirecting or running a script (either text or Python) + if not self.redirecting and not self._in_py and not self._script_dir: + # Here is the meaning of the various flags we are using with the less command: + # -S causes lines longer than the screen width to be chopped (truncated) rather than wrapped + # -R causes ANSI "color" escape sequences to be output in raw form (i.e. colors are displayed) + # -X disables sending the termcap initialization and deinitialization strings to the terminal + # -F causes less to automatically exit if the entire file can be displayed on the first screen + pager_cmd = 'less -SRXF' + if sys.platform.startswith('win'): + pager_cmd = 'more' + self.pipe_proc = subprocess.Popen(pager_cmd, shell=True, stdin=subprocess.PIPE) + try: + self.pipe_proc.stdin.write(msg_str.encode('utf-8', 'replace')) + self.pipe_proc.stdin.close() + except (IOError, KeyboardInterrupt): + pass + + # Less doesn't respect ^C, but catches it for its own UI purposes (aborting search etc. inside less) + while True: + try: + self.pipe_proc.wait() + except KeyboardInterrupt: + pass + else: + break + self.pipe_proc = None + else: + self.stdout.write(msg_str) + except BROKEN_PIPE_ERROR: + # This occurs if a command's output is being piped to another process and that process closes before the + # command is finished. We intentionally don't print a warning message here since we know that stdout + # will be restored by the _restore_output() method. If you would like your application to print a + # warning message, then override this method. + pass + def colorize(self, val, color): """Given a string (``val``), returns that string wrapped in UNIX-style special characters that turn on (and then off) text color and style. @@ -1599,6 +1651,7 @@ class Cmd(cmd.Cmd): # Open each side of the pipe and set stdout accordingly # noinspection PyTypeChecker self.stdout = io.open(write_fd, write_mode) + self.redirecting = True # noinspection PyTypeChecker subproc_stdin = io.open(read_fd, read_mode) @@ -1612,6 +1665,7 @@ class Cmd(cmd.Cmd): self.pipe_proc = None self.kept_state.restore() self.kept_state = None + self.redirecting = False # Re-raise the exception raise ex @@ -1620,6 +1674,7 @@ class Cmd(cmd.Cmd): raise EnvironmentError('Cannot redirect to paste buffer; install ``xclip`` and re-run to enable') self.kept_state = Statekeeper(self, ('stdout',)) self.kept_sys = Statekeeper(sys, ('stdout',)) + self.redirecting = True if statement.parsed.outputTo: mode = 'w' if statement.parsed.output == 2 * self.redirector: @@ -1662,6 +1717,8 @@ class Cmd(cmd.Cmd): self.kept_sys.restore() self.kept_sys = None + self.redirecting = False + def _func_named(self, arg): """Gets the method name associated with a given command. diff --git a/examples/paged_output.py b/examples/paged_output.py new file mode 100755 index 00000000..171c1b3e --- /dev/null +++ b/examples/paged_output.py @@ -0,0 +1,29 @@ +#!/usr/bin/env python +# coding=utf-8 +"""A simple example demonstrating the using paged output via the ppaged() method. +""" +import functools + +import cmd2 +from cmd2 import with_argument_list + + +class PagedOutput(cmd2.Cmd): + """ Example cmd2 application where we create commands that just print the arguments they are called with.""" + + def __init__(self): + cmd2.Cmd.__init__(self) + + @with_argument_list + def do_page_file(self, args): + """Read in a text file and display its output in a pager.""" + with open(args[0], 'r') as f: + text = f.read() + self.ppaged(text) + + complete_page_file = functools.partial(cmd2.path_complete) + + +if __name__ == '__main__': + app = PagedOutput() + app.cmdloop() |