ipython/IPython/core/magic_arguments.py at master · rcgray/ipython · GitHub

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''' A decorator-based method of constructing IPython magics with `argparse`

option handling.

New magic functions can be defined like so::

from IPython.core.magic_arguments import (argument, magic_arguments,

parse_argstring)

@magic_arguments()

@argument('-o', '--option', help='An optional argument.')

@argument('arg', type=int, help='An integer positional argument.')

def magic_cool(self, arg):

""" A really cool magic command.

"""

args = parse_argstring(magic_cool, arg)

...

The `@magic_arguments` decorator marks the function as having argparse arguments.

The `@argument` decorator adds an argument using the same syntax as argparse's

`add_argument()` method. More sophisticated uses may also require the

`@argument_group` or `@kwds` decorator to customize the formatting and the

parsing.

Help text for the magic is automatically generated from the docstring and the

arguments::

In[1]: %cool?

%cool [-o OPTION] arg

A really cool magic command.

positional arguments:

arg An integer positional argument.

optional arguments:

-o OPTION, --option OPTION

An optional argument.

Inheritance diagram:

.. inheritance-diagram:: IPython.core.magic_arguments

:parts: 3

'''

#-----------------------------------------------------------------------------

# Distributed under the terms of the Modified BSD License.

# The full license is in the file COPYING.txt, distributed with this software.

#-----------------------------------------------------------------------------

import argparse

import re

# Our own imports

from IPython.core.error import UsageError

from IPython.utils.decorators import undoc

from IPython.utils.process import arg_split

from IPython.utils.text import dedent

NAME_RE = re.compile(r"[a-zA-Z][a-zA-Z0-9_-]*$")

@undoc

class MagicHelpFormatter(argparse.RawDescriptionHelpFormatter):

"""A HelpFormatter with a couple of changes to meet our needs.

"""

# Modified to dedent text.

def _fill_text(self, text, width, indent):

return argparse.RawDescriptionHelpFormatter._fill_text(self, dedent(text), width, indent)

# Modified to wrap argument placeholders in <> where necessary.

def _format_action_invocation(self, action):

if not action.option_strings:

metavar, = self._metavar_formatter(action, action.dest)(1)

return metavar

else:

parts = []

# if the Optional doesn't take a value, format is:

# -s, --long

if action.nargs == 0:

parts.extend(action.option_strings)

# if the Optional takes a value, format is:

# -s ARGS, --long ARGS

else:

default = action.dest.upper()

args_string = self._format_args(action, default)

# IPYTHON MODIFICATION: If args_string is not a plain name, wrap

# it in <> so it's valid RST.

if not NAME_RE.match(args_string):

args_string = "<%s>" % args_string

for option_string in action.option_strings:

parts.append('%s %s' % (option_string, args_string))

return ', '.join(parts)

# Override the default prefix ('usage') to our % magic escape,

# in a code block.

def add_usage(self, usage, actions, groups, prefix="::\n\n %"):

super(MagicHelpFormatter, self).add_usage(usage, actions, groups, prefix)

class MagicArgumentParser(argparse.ArgumentParser):

""" An ArgumentParser tweaked for use by IPython magics.

"""

def __init__(self,

prog=None,

usage=None,

description=None,

epilog=None,

parents=None,

formatter_class=MagicHelpFormatter,

prefix_chars='-',

argument_default=None,

conflict_handler='error',

add_help=False):

if parents is None:

parents = []

super(MagicArgumentParser, self).__init__(prog=prog, usage=usage,

description=description, epilog=epilog,

parents=parents, formatter_class=formatter_class,

prefix_chars=prefix_chars, argument_default=argument_default,

conflict_handler=conflict_handler, add_help=add_help)

def error(self, message):

""" Raise a catchable error instead of exiting.

"""

raise UsageError(message)

def parse_argstring(self, argstring):

""" Split a string into an argument list and parse that argument list.

"""

argv = arg_split(argstring)

return self.parse_args(argv)

def construct_parser(magic_func):

""" Construct an argument parser using the function decorations.

"""

kwds = getattr(magic_func, 'argcmd_kwds', {})

if 'description' not in kwds:

kwds['description'] = getattr(magic_func, '__doc__', None)

arg_name = real_name(magic_func)

parser = MagicArgumentParser(arg_name, **kwds)

# Reverse the list of decorators in order to apply them in the

# order in which they appear in the source.

group = None

for deco in magic_func.decorators[::-1]:

result = deco.add_to_parser(parser, group)

if result is not None:

group = result

# Replace the magic function's docstring with the full help text.

magic_func.__doc__ = parser.format_help()

return parser

def parse_argstring(magic_func, argstring):

""" Parse the string of arguments for the given magic function.

"""

return magic_func.parser.parse_argstring(argstring)

def real_name(magic_func):

""" Find the real name of the magic.

"""

magic_name = magic_func.__name__

if magic_name.startswith('magic_'):

magic_name = magic_name[len('magic_'):]

return getattr(magic_func, 'argcmd_name', magic_name)

class ArgDecorator(object):

""" Base class for decorators to add ArgumentParser information to a method.

"""

def __call__(self, func):

if not getattr(func, 'has_arguments', False):

func.has_arguments = True

func.decorators = []

func.decorators.append(self)

return func

def add_to_parser(self, parser, group):

""" Add this object's information to the parser, if necessary.

"""

pass

class magic_arguments(ArgDecorator):

""" Mark the magic as having argparse arguments and possibly adjust the

name.

"""

def __init__(self, name=None):

self.name = name

def __call__(self, func):

if not getattr(func, 'has_arguments', False):

func.has_arguments = True

func.decorators = []

if self.name is not None:

func.argcmd_name = self.name

# This should be the first decorator in the list of decorators, thus the

# last to execute. Build the parser.

func.parser = construct_parser(func)

return func

class ArgMethodWrapper(ArgDecorator):

"""

Base class to define a wrapper for ArgumentParser method.

Child class must define either `_method_name` or `add_to_parser`.

"""

_method_name = None

def __init__(self, *args, **kwds):

self.args = args

self.kwds = kwds

def add_to_parser(self, parser, group):

""" Add this object's information to the parser.

"""

if group is not None:

parser = group

getattr(parser, self._method_name)(*self.args, **self.kwds)

return None

class argument(ArgMethodWrapper):

""" Store arguments and keywords to pass to add_argument().

Instances also serve to decorate command methods.

"""

_method_name = 'add_argument'

class defaults(ArgMethodWrapper):

""" Store arguments and keywords to pass to set_defaults().

Instances also serve to decorate command methods.

"""

_method_name = 'set_defaults'

class argument_group(ArgMethodWrapper):

""" Store arguments and keywords to pass to add_argument_group().

Instances also serve to decorate command methods.

"""

def add_to_parser(self, parser, group):

""" Add this object's information to the parser.

"""

return parser.add_argument_group(*self.args, **self.kwds)

class kwds(ArgDecorator):

""" Provide other keywords to the sub-parser constructor.

"""

def __init__(self, **kwds):

self.kwds = kwds

def __call__(self, func):

func = super(kwds, self).__call__(func)

func.argcmd_kwds = self.kwds

return func

__all__ = ['magic_arguments', 'argument', 'argument_group', 'kwds',

'parse_argstring']

ipython/IPython/core/magic_arguments.py at master · rcgray/ipython · GitHub

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