diff options
Diffstat (limited to 'cmd2/pyscript_bridge.py')
| -rw-r--r-- | cmd2/pyscript_bridge.py | 38 |
1 files changed, 28 insertions, 10 deletions
diff --git a/cmd2/pyscript_bridge.py b/cmd2/pyscript_bridge.py index 6c14ff1d..f3ce841d 100644 --- a/cmd2/pyscript_bridge.py +++ b/cmd2/pyscript_bridge.py @@ -25,9 +25,27 @@ class CommandResult(namedtuple_with_defaults('CommandResult', ['stdout', 'stderr Named tuple attributes ---------------------- stdout: str - Output captured from stdout while this command is executing - stderr: str - Output captured from stderr while this command is executing. None if no error captured + stderr: str - Output captured from stderr while this command is executing. None if no error captured. data - Data returned by the command. + Any combination of these fields can be used when developing a scripting API for a given command. + By default stdout and stderr will be captured for you. If there is additional command specific data, + then write that to cmd2's _last_result member. That becomes the data member of this tuple. + + In some cases, the data member may contain everything needed for a command and storing stdout + and stderr might just be a duplication of data that wastes memory. In that case, the StdSim can + be told not to store output with its pause_storage member. While this member is True, any output + sent to StdSim won't be saved in its buffer. + + The code would look like this: + if isinstance(self.stdout, StdSim): + self.stdout.pause_storage = True + + if isinstance(sys.stderr, StdSim): + sys.stderr.pause_storage = True + + See StdSim class in utils.py for more information + NOTE: Named tuples are immutable. So the contents are there for access, not for modification. """ def __bool__(self) -> bool: @@ -67,25 +85,25 @@ class PyscriptBridge(object): if echo is None: echo = self.cmd_echo - copy_stdout = StdSim(sys.stdout, echo) - copy_stderr = StdSim(sys.stderr, echo) - + # This will be used to capture _cmd2_app.stdout and sys.stdout copy_cmd_stdout = StdSim(self._cmd2_app.stdout, echo) + # This will be used to capture sys.stderr + copy_stderr = StdSim(sys.stderr, echo) + self._cmd2_app._last_result = None try: self._cmd2_app.stdout = copy_cmd_stdout - with redirect_stdout(copy_stdout): + with redirect_stdout(copy_cmd_stdout): with redirect_stderr(copy_stderr): # Include a newline in case it's a multiline command self._cmd2_app.onecmd_plus_hooks(command + '\n') finally: self._cmd2_app.stdout = copy_cmd_stdout.inner_stream - # if stderr is empty, set it to None - stderr = copy_stderr.getvalue() if copy_stderr.getvalue() else None - - outbuf = copy_cmd_stdout.getvalue() if copy_cmd_stdout.getvalue() else copy_stdout.getvalue() - result = CommandResult(stdout=outbuf, stderr=stderr, data=self._cmd2_app._last_result) + # Save the output. If stderr is empty, set it to None. + result = CommandResult(stdout=copy_cmd_stdout.getvalue(), + stderr=copy_stderr.getvalue() if copy_stderr.getvalue() else None, + data=self._cmd2_app._last_result) return result |