Skip to main content

convenience functions for working with the Cmd module and other command line related stuff

Project description

Class BaseCommand

A base class for handling nestable command lines.

This class provides the basic parse and dispatch mechanisms for command lines. To implement a command line one instantiates a subclass of BaseCommand:

class MyCommand(BaseCommand): GETOPT_SPEC = 'ab:c' ... the_cmd = MyCommand()

Running a command is done by:

the_cmd.run(argv)

The subclass is customised by overriding the following methods:

  • apply_defaults(options): prepare the initial state of options before any command line options are applied
  • apply_opts(options,opts): apply the opts to options. opts is an option value mapping as returned by getopot.getopt.
  • cmd_subcmd(argv,options): if the command line options are followed by an argument whose value is subcmd, then method cmd_subcmd(argv,options) will be called where argv contains the command line arguments after subcmd.
  • main(argv,options): if there are no command line aguments after the options or the first argument does not have a corresponding cmd_subcmd method then method main(argv,options) will be called where argv contains the command line arguments.
  • run_context(argv,options,cmd=None): a context manager to provide setup or teardown actions to occur before and after the command implementation respectively. If the implementation is a cmd_subcmd method then this is called with cmd=*subcmd; if the implementation is mainthen this is called withcmd=None`.

To aid recursive use it is intended that all the per command state is contained in the options object and therefore that in typical use all of apply_opts, cmd_subcmd, mainandrun_contextshould be static methods making no reference toself`.

Editorial: why not arparse? Primarily because when incorrectly invoked an argparse command line prints the help/usage messgae and aborts the whole programme with SystemExit.

Method BaseCommand.__init__(self, getopt_spec=None)

Initialise the BaseCommand.

Parameters:

  • getopt_spec: optional getopt.getopt compatible option specifier. The default comes from the class' .GETOPT_SPEC attribute.

Function docmd(dofunc)

Decorator for Cmd subclass methods to supply some basic quality of service.

This decorator:

  • wraps the function call in a cs.pfx.Pfx for context
  • intercepts getopt.GetoptErrors, issues a warning and runs self.do_help with the method name, then returns None
  • intercepts other Exceptions, issues an exception log message and returns None

The intended use is to decorate cmd.Cmd do_* methods:

@docmd def do_something(...): ... do something ...

Project details


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

cs.cmdutils-20190617.2.tar.gz (4.8 kB view hashes)

Uploaded Source

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page