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"""optik.help
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Provides HelpFormatter and subclasses -- used by OptionParser
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to generate formatted help text.
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"""
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# Copyright (c) 2001-2004 Gregory P. Ward. All rights reserved.
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# See the README.txt distributed with Optik for licensing terms.
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import os
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import string
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import textwrap
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from optik.option import NO_DEFAULT
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from optik.errors import gettext
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_ = gettext
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__revision__ = "$Id: help.py,v 1.1 2009/02/05 23:03:30 stechong Exp $"
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__all__ = ['HelpFormatter', 'IndentedHelpFormatter', 'TitledHelpFormatter']
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class HelpFormatter:
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"""
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Abstract base class for formatting option help. OptionParser
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instances should use one of the HelpFormatter subclasses for
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formatting help; by default IndentedHelpFormatter is used.
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Instance attributes:
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parser : OptionParser
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the controlling OptionParser instance
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indent_increment : int
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the number of columns to indent per nesting level
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max_help_position : int
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the maximum starting column for option help text
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help_position : int
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the calculated starting column for option help text;
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initially the same as the maximum
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width : int
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total number of columns for output (pass None to constructor for
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this value to be taken from the $COLUMNS environment variable)
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level : int
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current indentation level
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current_indent : int
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current indentation level (in columns)
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help_width : int
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number of columns available for option help text (calculated)
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default_tag : str
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text to replace with each option's default value, "%default"
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by default. Set to false value to disable default value expansion.
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option_strings : { Option : str }
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maps Option instances to the snippet of help text explaining
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the syntax of that option, e.g. "-h, --help" or
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"-fFILE, --file=FILE"
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_short_opt_fmt : str
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format string controlling how short options with values are
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printed in help text. Must be either "%s%s" ("-fFILE") or
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"%s %s" ("-f FILE"), because those are the two syntaxes that
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Optik supports.
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_long_opt_fmt : str
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similar but for long options; must be either "%s %s" ("--file FILE")
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or "%s=%s" ("--file=FILE").
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"""
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NO_DEFAULT_VALUE = "none"
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def __init__(self,
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indent_increment,
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max_help_position,
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width,
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short_first):
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self.parser = None
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self.indent_increment = indent_increment
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self.help_position = self.max_help_position = max_help_position
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if width is None:
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try:
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width = int(os.environ['COLUMNS'])
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except (KeyError, ValueError):
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width = 80
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width = width - 2
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self.width = width
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self.current_indent = 0
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self.level = 0
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self.help_width = None # computed later
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self.short_first = short_first
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self.default_tag = "%default"
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self.option_strings = {}
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self._short_opt_fmt = "%s %s"
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self._long_opt_fmt = "%s=%s"
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def set_parser(self, parser):
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self.parser = parser
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def set_short_opt_delimiter(self, delim):
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if delim not in ("", " "):
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raise ValueError(
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"invalid metavar delimiter for short options: %r" % delim)
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self._short_opt_fmt = "%s" + delim + "%s"
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def set_long_opt_delimiter(self, delim):
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if delim not in ("=", " "):
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raise ValueError(
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"invalid metavar delimiter for long options: %r" % delim)
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self._long_opt_fmt = "%s" + delim + "%s"
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def indent(self):
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self.current_indent = self.current_indent + self.indent_increment
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self.level = self.level + 1
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def dedent(self):
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self.current_indent = self.current_indent - self.indent_increment
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assert self.current_indent >= 0, "Indent decreased below 0."
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self.level = self.level - 1
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def format_usage(self, usage):
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raise NotImplementedError, "subclasses must implement"
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def format_heading(self, heading):
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raise NotImplementedError, "subclasses must implement"
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def format_description(self, description):
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if not description:
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return ""
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desc_width = self.width - self.current_indent
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indent = " "*self.current_indent
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return textwrap.fill(description,
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desc_width,
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initial_indent=indent,
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subsequent_indent=indent) + "\n"
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def expand_default(self, option):
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if self.parser is None or not self.default_tag:
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return option.help
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default_value = self.parser.defaults.get(option.dest)
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if default_value is NO_DEFAULT or default_value is None:
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default_value = self.NO_DEFAULT_VALUE
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return string.replace(option.help, self.default_tag, str(default_value))
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def format_option(self, option):
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# The help for each option consists of two parts:
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# * the opt strings and metavars
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# eg. ("-x", or "-fFILENAME, --file=FILENAME")
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# * the user-supplied help string
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# eg. ("turn on expert mode", "read data from FILENAME")
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#
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# If possible, we write both of these on the same line:
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# -x turn on expert mode
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#
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# But if the opt string list is too long, we put the help
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# string on a second line, indented to the same column it would
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# start in if it fit on the first line.
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# -fFILENAME, --file=FILENAME
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# read data from FILENAME
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result = []
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opts = self.option_strings[option]
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opt_width = self.help_position - self.current_indent - 2
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if len(opts) > opt_width:
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opts = "%*s%s\n" % (self.current_indent, "", opts)
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indent_first = self.help_position
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else: # start help on same line as opts
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opts = "%*s%-*s " % (self.current_indent, "", opt_width, opts)
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indent_first = 0
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result.append(opts)
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if option.help:
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help_text = self.expand_default(option)
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help_lines = textwrap.wrap(help_text, self.help_width)
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result.append("%*s%s\n" % (indent_first, "", help_lines[0]))
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for line in help_lines[1:]:
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result.append("%*s%s\n" % (self.help_position, "", line))
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elif opts[-1] != "\n":
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result.append("\n")
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return string.join(result, "")
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def store_option_strings(self, parser):
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self.indent()
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max_len = 0
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for opt in parser.option_list:
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strings = self.format_option_strings(opt)
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self.option_strings[opt] = strings
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max_len = max(max_len, len(strings) + self.current_indent)
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self.indent()
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for group in parser.option_groups:
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for opt in group.option_list:
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strings = self.format_option_strings(opt)
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self.option_strings[opt] = strings
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max_len = max(max_len, len(strings) + self.current_indent)
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self.dedent()
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self.dedent()
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self.help_position = min(max_len + 2, self.max_help_position)
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self.help_width = self.width - self.help_position
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def format_option_strings(self, option):
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"""Return a comma-separated list of option strings & metavariables."""
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if option.takes_value():
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metavar = option.metavar or string.upper(option.dest)
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short_opts = []
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for sopt in option._short_opts:
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short_opts.append(self._short_opt_fmt % (sopt, metavar))
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long_opts = []
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for lopt in option._long_opts:
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long_opts.append(self._long_opt_fmt % (lopt, metavar))
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else:
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short_opts = option._short_opts
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long_opts = option._long_opts
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if self.short_first:
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opts = short_opts + long_opts
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else:
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opts = long_opts + short_opts
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return string.join(opts, ", ")
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class IndentedHelpFormatter (HelpFormatter):
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"""Format help with indented section bodies.
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"""
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def __init__(self,
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indent_increment=2,
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max_help_position=24,
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width=None,
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short_first=1):
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HelpFormatter.__init__(
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self, indent_increment, max_help_position, width, short_first)
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def format_usage(self, usage):
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return _("usage: %s\n") % usage
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def format_heading(self, heading):
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return "%*s%s:\n" % (self.current_indent, "", heading)
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class TitledHelpFormatter (HelpFormatter):
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"""Format help with underlined section headers.
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"""
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def __init__(self,
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indent_increment=0,
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max_help_position=24,
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width=None,
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short_first=0):
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HelpFormatter.__init__ (
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self, indent_increment, max_help_position, width, short_first)
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def format_usage(self, usage):
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return "%s %s\n" % (self.format_heading(_("Usage")), usage)
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def format_heading(self, heading):
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return "%s\n%s\n" % (heading, "=-"[self.level] * len(heading))
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