ENH: Add the argparse-based option parsing for magics.

IPython/core/magic_arguments.py

@@ -0,0 +1,222 b''
+''' 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.
+
+'''
+#-----------------------------------------------------------------------------
+# Copyright (c) 2010, IPython Development Team.
+#
+# Distributed under the terms of the Modified BSD License.
+#
+# The full license is in the file COPYING.txt, distributed with this software.
+#-----------------------------------------------------------------------------
+
+# Stdlib imports
+import shlex
+
+# Our own imports
+from IPython.external import argparse
+from IPython.core.error import UsageError
+
+
+class MagicArgumentParser(argparse.ArgumentParser):
+    """ An ArgumentParser tweaked for use by IPython magics.
+    """
+    def __init__(self,
+                 prog=None,
+                 usage=None,
+                 description=None,
+                 epilog=None,
+                 version=None,
+                 parents=None,
+                 formatter_class=argparse.HelpFormatter,
+                 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, version=version,
+            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 = shlex.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 starting 'usage: ' with IPython's %.
+    help_text = parser.format_help()
+    if help_text.startswith('usage: '):
+        help_text = help_text.replace('usage: ', '%', 1)
+    else:
+        help_text = '%' + help_text
+
+    # Replace the magic function's docstring with the full help text.
+    magic_func.__doc__ = help_text
+
+    return parser
+
+
+def parse_argstring(magic_func, argstring):
+    """ Parse the string of arguments for the given magic function.
+    """
+    args = magic_func.parser.parse_argstring(argstring)
+    return args
+
+
+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_'):]
+    arg_name = getattr(magic_func, 'argcmd_name', magic_name)
+    return arg_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 argument(ArgDecorator):
+    """ Store arguments and keywords to pass to add_argument().
+
+    Instances also serve to decorate command methods.
+    """
+    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
+        parser.add_argument(*self.args, **self.kwds)
+        return None
+
+
+class argument_group(ArgDecorator):
+    """ Store arguments and keywords to pass to add_argument_group().
+
+    Instances also serve to decorate command methods.
+    """
+    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.
+        """
+        group = parser.add_argument_group(*self.args, **self.kwds)
+        return group
+
+
+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/core/tests/test_magic_arguments.py

@@ -0,0 +1,113 b''
+#-----------------------------------------------------------------------------
+# Copyright (c) 2010, IPython Development Team.
+#
+# Distributed under the terms of the Modified BSD License.
+#
+# The full license is in the file COPYING.txt, distributed with this software.
+#-----------------------------------------------------------------------------
+
+from nose.tools import assert_equal, assert_true
+
+from IPython.external import argparse
+from IPython.core.magic_arguments import (argument, argument_group, kwds,
+    magic_arguments, parse_argstring, real_name)
+
+
+@magic_arguments()
+@argument('-f', '--foo', help="an argument")
+def magic_foo1(self, args):
+    """ A docstring.
+    """
+    return parse_argstring(magic_foo1, args)
+
+@magic_arguments()
+def magic_foo2(self, args):
+    """ A docstring.
+    """
+    return parse_argstring(magic_foo2, args)
+
+@magic_arguments()
+@argument('-f', '--foo', help="an argument")
+@argument_group('Group')
+@argument('-b', '--bar', help="a grouped argument")
+@argument_group('Second Group')
+@argument('-z', '--baz', help="another grouped argument")
+def magic_foo3(self, args):
+    """ A docstring.
+    """
+    return parse_argstring(magic_foo3, args)
+
+@magic_arguments()
+@kwds(argument_default=argparse.SUPPRESS)
+@argument('-f', '--foo', help="an argument")
+def magic_foo4(self, args):
+    """ A docstring.
+    """
+    return parse_argstring(magic_foo4, args)
+
+@magic_arguments('frobnicate')
+@argument('-f', '--foo', help="an argument")
+def magic_foo5(self, args):
+    """ A docstring.
+    """
+    return parse_argstring(magic_foo5, args)
+
+@magic_arguments()
+@argument('-f', '--foo', help="an argument")
+def magic_magic_foo(self, args):
+    """ A docstring.
+    """
+    return parse_argstring(magic_magic_foo, args)
+
+@magic_arguments()
+@argument('-f', '--foo', help="an argument")
+def foo(self, args):
+    """ A docstring.
+    """
+    return parse_argstring(foo, args)
+
+def test_magic_arguments():
+    # Ideally, these would be doctests, but I could not get it to work.
+    yield assert_equal, magic_foo1.__doc__, '%foo1 [-f FOO]\n\nA docstring.\n\noptional arguments:\n  -f FOO, --foo FOO  an argument\n'
+    yield assert_equal, getattr(magic_foo1, 'argcmd_name', None), None
+    yield assert_equal, real_name(magic_foo1), 'foo1'
+    yield assert_equal, magic_foo1(None, ''), argparse.Namespace(foo=None)
+    yield assert_true, hasattr(magic_foo1, 'has_arguments')
+
+    yield assert_equal, magic_foo2.__doc__, '%foo2\n\nA docstring.\n'
+    yield assert_equal, getattr(magic_foo2, 'argcmd_name', None), None
+    yield assert_equal, real_name(magic_foo2), 'foo2'
+    yield assert_equal, magic_foo2(None, ''), argparse.Namespace()
+    yield assert_true, hasattr(magic_foo2, 'has_arguments')
+
+    yield assert_equal, magic_foo3.__doc__, '%foo3 [-f FOO] [-b BAR] [-z BAZ]\n\nA docstring.\n\noptional arguments:\n  -f FOO, --foo FOO  an argument\n\nGroup:\n  -b BAR, --bar BAR  a grouped argument\n\nSecond Group:\n  -z BAZ, --baz BAZ  another grouped argument\n'
+    yield assert_equal, getattr(magic_foo3, 'argcmd_name', None), None
+    yield assert_equal, real_name(magic_foo3), 'foo3'
+    yield assert_equal, magic_foo3(None, ''), argparse.Namespace(bar=None, baz=None, foo=None)
+    yield assert_true, hasattr(magic_foo3, 'has_arguments')
+
+    yield assert_equal, magic_foo4.__doc__, '%foo4 [-f FOO]\n\nA docstring.\n\noptional arguments:\n  -f FOO, --foo FOO  an argument\n'
+    yield assert_equal, getattr(magic_foo4, 'argcmd_name', None), None
+    yield assert_equal, real_name(magic_foo4), 'foo4'
+    yield assert_equal, magic_foo4(None, ''), argparse.Namespace()
+    yield assert_true, hasattr(magic_foo4, 'has_arguments')
+
+    yield assert_equal, magic_foo5.__doc__, '%frobnicate [-f FOO]\n\nA docstring.\n\noptional arguments:\n  -f FOO, --foo FOO  an argument\n'
+    yield assert_equal, getattr(magic_foo5, 'argcmd_name', None), 'frobnicate'
+    yield assert_equal, real_name(magic_foo5), 'frobnicate'
+    yield assert_equal, magic_foo5(None, ''), argparse.Namespace(foo=None)
+    yield assert_true, hasattr(magic_foo5, 'has_arguments')
+
+    yield assert_equal, magic_magic_foo.__doc__, '%magic_foo [-f FOO]\n\nA docstring.\n\noptional arguments:\n  -f FOO, --foo FOO  an argument\n'
+    yield assert_equal, getattr(magic_magic_foo, 'argcmd_name', None), None
+    yield assert_equal, real_name(magic_magic_foo), 'magic_foo'
+    yield assert_equal, magic_magic_foo(None, ''), argparse.Namespace(foo=None)
+    yield assert_true, hasattr(magic_magic_foo, 'has_arguments')
+
+    yield assert_equal, foo.__doc__, '%foo [-f FOO]\n\nA docstring.\n\noptional arguments:\n  -f FOO, --foo FOO  an argument\n'
+    yield assert_equal, getattr(foo, 'argcmd_name', None), None
+    yield assert_equal, real_name(foo), 'foo'
+    yield assert_equal, foo(None, ''), argparse.Namespace(foo=None)
+    yield assert_true, hasattr(foo, 'has_arguments')
+
+