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# coding: utf-8
#
# Copyright © 2010—2014 Andrey Mikhaylenko and contributors
#
# This file is part of Argh.
#
# Argh is free software under terms of the GNU Lesser
# General Public License version 3 (LGPLv3) as published by the Free
# Software Foundation. See the file README.rst for copying conditions.
#
import argparse
__all__ = (
'ATTR_NAME', 'ATTR_ALIASES', 'ATTR_ARGS', 'ATTR_WRAPPED_EXCEPTIONS',
'ATTR_WRAPPED_EXCEPTIONS_PROCESSOR', 'ATTR_EXPECTS_NAMESPACE_OBJECT',
'PARSER_FORMATTER', 'DEFAULT_ARGUMENT_TEMPLATE', 'DEST_FUNCTION',
)
#
# Names of function attributes where Argh stores command behaviour
#
#: explicit command name (differing from function name)
ATTR_NAME = 'argh_name'
#: alternative command names
ATTR_ALIASES = 'argh_aliases'
#: declared arguments
ATTR_ARGS = 'argh_args'
#: list of exception classes that should be wrapped and printed as results
ATTR_WRAPPED_EXCEPTIONS = 'argh_wrap_errors'
#: a function to preprocess the exception object when it is wrapped
ATTR_WRAPPED_EXCEPTIONS_PROCESSOR = 'argh_wrap_errors_processor'
#: forcing argparse.Namespace object instead of signature introspection
ATTR_EXPECTS_NAMESPACE_OBJECT = 'argh_expects_namespace_object'
#
# Dest names in parser defaults
#
#: dest name for a function mapped to given endpoint (goes to Namespace obj)
DEST_FUNCTION = 'function'
#
# Other library-wide stuff
#
class CustomFormatter(argparse.ArgumentDefaultsHelpFormatter,
argparse.RawDescriptionHelpFormatter):
def _expand_help(self, action):
"""
This method is copied verbatim from ArgumentDefaultsHelpFormatter with
a couple of lines added just before the end. Reason: we need to
`repr()` default values instead of simply inserting them as is.
This helps notice, for example, an empty string as the default value;
moreover, it prevents breaking argparse due to logical quirks inside
of its formatters.
Ideally this could be achieved by simply defining
:attr:`DEFAULT_ARGUMENT_TEMPLATE` as ``{default!r}`` but unfortunately
argparse only supports the old printf syntax.
"""
params = dict(vars(action), prog=self._prog)
for name in list(params):
if params[name] is argparse.SUPPRESS:
del params[name]
for name in list(params):
if hasattr(params[name], '__name__'):
params[name] = params[name].__name__
if params.get('choices') is not None:
choices_str = ', '.join([str(c) for c in params['choices']])
params['choices'] = choices_str
# XXX this is added in Argh vs. argparse.ArgumentDefaultsHelpFormatter
# (avoiding empty strings, otherwise Argparse would die with
# an IndexError in _format_action)
#
if 'default' in params:
if params['default'] is None:
params['default'] = '-'
else:
params['default'] = repr(params['default'])
#
# /
return self._get_help_string(action) % params
#: Default formatter to be used in implicitly instantiated ArgumentParser.
PARSER_FORMATTER = CustomFormatter
DEFAULT_ARGUMENT_TEMPLATE = '%(default)s'
"""
Default template of argument help message (see issue #64).
The template ``%(default)s`` is used by `argparse` to display the argument's
default value.
"""