#! /usr/bin/env python
# Author: Marc Claesen
#
# Copyright (c) 2014 KU Leuven, ESAT-STADIUS
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# 3. Neither name of copyright holders nor the names of its contributors
# may be used to endorse or promote products derived from this software
# without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR
# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
import collections
import itertools
import inspect
[docs]def nth(iterable, n):
"""Returns the nth item from iterable."""
try:
return iterable[n]
except TypeError:
try:
return next(itertools.islice(iterable, n, None))
except StopIteration:
raise IndexError('index out of range')
[docs]def DocumentedNamedTuple(docstring, *ntargs):
"""Factory function to construct collections.namedtuple with
a docstring. Useful to attach meta-information to data structures.
Inspired by http://stackoverflow.com/a/1606478"""
nt = collections.namedtuple(*ntargs)
class NT(nt):
__doc__ = docstring
return NT
[docs]def get_default_args(func):
"""
returns a dictionary of arg_name:default_values for the input function
"""
if not callable(func):
raise TypeError("%s is not callable" % type(func))
if inspect.isfunction(func):
print('a')
spec = inspect.getargspec(func)
elif hasattr(func, 'im_func'):
print('b')
spec = inspect.getargspec(func.im_func)
print(spec)
elif inspect.isclass(func):
print('c')
return get_default_args(func.__init__)
elif isinstance(func, object):
print('d')
# We already know the instance is callable,
# so it must have a __call__ method defined.
# Return the arguments it expects.
return get_default_args(func.__call__)
try:
return dict(zip(reversed(spec.args), reversed(spec.defaults)))
except TypeError:
# list of defaults and/or args are empty
return {}
# taken from http://kbyanc.blogspot.be/2007/07/python-more-generic-getargspec.html
[docs]def getargspec(obj):
"""Get the names and default values of a callable's
arguments
A tuple of four things is returned: (args, varargs,
varkw, defaults).
- args is a list of the argument names (it may
contain nested lists).
- varargs and varkw are the names of the * and
** arguments or None.
- defaults is a tuple of default argument values
or None if there are no default arguments; if
this tuple has n elements, they correspond to
the last n elements listed in args.
Unlike inspect.getargspec(), can return argument
specification for functions, methods, callable
objects, and classes. Does not support builtin
functions or methods.
"""
if not callable(obj):
raise TypeError("%s is not callable" % type(obj))
try:
if inspect.isfunction(obj):
return inspect.getargspec(obj)
elif hasattr(obj, 'im_func'):
# For methods or classmethods drop the first
# argument from the returned list because
# python supplies that automatically for us.
# Note that this differs from what
# inspect.getargspec() returns for methods.
# NB: We use im_func so we work with
# instancemethod objects also.
spec = list(inspect.getargspec(obj.im_func))
spec[0] = spec[0][1:]
return spec
elif inspect.isclass(obj):
return getargspec(obj.__init__)
#elif isinstance(obj, object) and \
# not isinstance(obj, type(arglist.__get__)): # TODO: what does this clause do?
elif isinstance(obj, object):
# We already know the instance is callable,
# so it must have a __call__ method defined.
# Return the arguments it expects.
return getargspec(obj.__call__)
except NotImplementedError:
# If a nested call to our own getargspec()
# raises NotImplementedError, re-raise the
# exception with the real object type to make
# the error message more meaningful (the caller
# only knows what they passed us; they shouldn't
# care what aspect(s) of that object we actually
# examined).
pass
raise NotImplementedError("do not know how to get argument list for %s" % type(obj))