Python 2.7 quick reference |  |
Python 2.7 quick reference | |
These methods are available on your ArgumentParser instance:
.print_usage(file=None)
Prints the short summary of argument usage. The
default file is sys.stdout.
.print_help(file=None)
Prints the full summary of argument usage, including
the help text for each argument. The default file is sys.stdout.
.format_usage()
Formats the short summary of argument usage and returns it as a string.
.format_help()
Formats the full help text and returns it as a string.
.exit(status=0, message=None)
Terminates execution with status 0 (or the status value you provide). If you provide a
message string, that message will be
printed before termination.
.error(message)
Prints the usage message, plus the message string you provide, then terminates
execution with status 2.
.add_mutually_exclusive_group(required=False)
If you have two or more options that cannot be
specified on the same command line, use this method to
create an option group. Then call the .add_argument() on the group instance to add these options. If
you specify required=True, the user is
required supply one of the options in the group.
Suppose for example that you have two mutually
exclusive options --english and --metric. This code would prohibit the user
from specifying both at once:
p = argparse.ArgumentParser()
g = p.add_mutually_exclusive_group()
g.add_argument("-e", "--english", dest="isMetric", action="store_false")
g.add_argument("-m", "--metric", dest="isMetric", action="store_true")
.set_defaults(**kw)
Use this method to specify the default values of any
variable. For each keyword argument n=vn.parse_args() will have
value v
For example, if you have two mutually exclusive
options, but you don't require one or the other, the
.set_defaults() method is a good way to
specify the value of the option when neither is given.
Here is an interactive example showing this technique.
>>> parser = argparse.ArgumentParser()
>>> group = parser.add_mutually_exclusive_group()
>>> group.add_argument("-y", "--yes", dest="which", action="store_true")
>>> group.add_argument("-n", "--no", dest="which", action="store_false")
>>> parser.set_defaults(which=True)
>>> print parser.parse_args(["--no"])
Namespace(which=False)
>>> print parser.parse_args(["-y"])
Namespace(which=True)
>>> print parser.parse_args([])
Namespace(which=True)