Module: core.magic_arguments

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.

Here is an elaborated example that uses default parameters in argument and calls the args in the cell magic:

from IPython.core.magic import register_cell_magic
from IPython.core.magic_arguments import (argument, magic_arguments,
                                        parse_argstring)


@magic_arguments()
@argument(
    "--option",
    "-o",
    help=("Add an option here"),
)
@argument(
    "--style",
    "-s",
    default="foo",
    help=("Add some style arguments"),
)
@register_cell_magic
def my_cell_magic(line, cell):
    args = parse_argstring(my_cell_magic, line)
    print(f"{args.option=}")
    print(f"{args.style=}")
    print(f"{cell=}")

In a jupyter notebook, this cell magic can be executed like this:

%%my_cell_magic -o Hello
print("bar")
i = 42

Inheritance diagram:

8 Classes

class IPython.core.magic_arguments.MagicArgumentParser(prog=None, usage=None, description=None, epilog=None, parents=None, formatter_class=<class 'IPython.core.magic_arguments.MagicHelpFormatter'>, prefix_chars='-', argument_default=None, conflict_handler='error', add_help=False)

Bases: ArgumentParser

An ArgumentParser tweaked for use by IPython magics.

__init__(prog=None, usage=None, description=None, epilog=None, parents=None, formatter_class=<class 'IPython.core.magic_arguments.MagicHelpFormatter'>, prefix_chars='-', argument_default=None, conflict_handler='error', add_help=False)

error(message)

Raise a catchable error instead of exiting.

parse_argstring(argstring, *, partial=False)

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

class IPython.core.magic_arguments.ArgDecorator

Bases: object

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

add_to_parser(parser, group)

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

class IPython.core.magic_arguments.magic_arguments(name=None)

Bases: ArgDecorator

Mark the magic as having argparse arguments and possibly adjust the name.

__init__(name=None)

class IPython.core.magic_arguments.ArgMethodWrapper(*args, **kwds)

Bases: ArgDecorator

Base class to define a wrapper for ArgumentParser method.

Child class must define either _method_name or add_to_parser.

__init__(*args, **kwds)

add_to_parser(parser, group)

Add this object’s information to the parser.

class IPython.core.magic_arguments.argument(*args, **kwds)

Bases: ArgMethodWrapper

Store arguments and keywords to pass to add_argument().

Instances also serve to decorate command methods.

class IPython.core.magic_arguments.defaults(*args, **kwds)

Bases: ArgMethodWrapper

Store arguments and keywords to pass to set_defaults().

Instances also serve to decorate command methods.

class IPython.core.magic_arguments.argument_group(*args, **kwds)

Bases: ArgMethodWrapper

Store arguments and keywords to pass to add_argument_group().

Instances also serve to decorate command methods.

add_to_parser(parser, group)

Add this object’s information to the parser.

class IPython.core.magic_arguments.kwds(**kwds)

Bases: ArgDecorator

Provide other keywords to the sub-parser constructor.

__init__(**kwds)

3 Functions

IPython.core.magic_arguments.construct_parser(magic_func)

Construct an argument parser using the function decorations.

IPython.core.magic_arguments.parse_argstring(magic_func, argstring, *, partial=False)

Parse the string of arguments for the given magic function.

IPython.core.magic_arguments.real_name(magic_func)

Find the real name of the magic.