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########################## LICENCE ###############################
##
## Copyright (c) 2010, Michele Simionato
## All rights reserved.
##
## Redistributions of source code must retain the above copyright
## notice, this list of conditions and the following disclaimer.
## Redistributions in bytecode 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.
## 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 COPYRIGHT
## HOLDERS 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.
"""
plac, the easiest Command Line Arguments Parser in the world.
See plac/doc.html for the documentation.
"""
# this module should be kept Python 2.3 compatible
__version__ = '0.4.0'
import re, sys, inspect, argparse
if sys.version >= '3':
from inspect import getfullargspec
else:
class getfullargspec(object):
"A quick and dirty replacement for getfullargspec for Python 2.X"
def __init__(self, f):
self.args, self.varargs, self.keywords, self.defaults = \
inspect.getargspec(f)
self.annotations = getattr(f, '__annotations__', {})
try:
set
except NameError: # Python 2.3
from sets import Set as set
def annotations(**ann):
"""
Returns a decorator annotating a function with the given annotations.
This is a trick to support function annotations in Python 2.X.
"""
def annotate(f):
fas = getfullargspec(f)
args = fas.args
if fas.varargs:
args.append(fas.varargs)
if fas.keywords:
args.append(fas.keywords)
for argname in ann:
if argname not in args:
raise NameError(
'Annotating non-existing argument: %s' % argname)
f.__annotations__ = ann
return f
return annotate
def is_annotation(obj):
"""
An object is an annotation object if it has the attributes
help, kind, abbrev, type, choices, metavar.
"""
return (hasattr(obj, 'help') and hasattr(obj, 'kind') and
hasattr(obj, 'abbrev') and hasattr(obj, 'type')
and hasattr(obj, 'choices') and hasattr(obj, 'metavar'))
class Annotation(object):
def __init__(self, help="", kind="positional", abbrev=None, type=None,
choices=None, metavar=None):
assert kind in ('positional', 'option', 'flag'), kind
if kind == "positional":
assert abbrev is None, abbrev
self.help = help
self.kind = kind
self.abbrev = abbrev
self.type = type
self.choices = choices
self.metavar = metavar
def from_(cls, obj):
"Helper to convert an object into an annotation, if needed"
if is_annotation(obj):
return obj # do nothing
elif hasattr(obj, '__iter__') and not isinstance(obj, str):
return cls(*obj)
return cls(obj)
from_ = classmethod(from_)
NONE = object() # sentinel use to signal the absence of a default
valid_attrs = getfullargspec(argparse.ArgumentParser.__init__).args[1:]
def parser_from(func):
"""
Extract the arguments from the attributes of the passed function and
return an ArgumentParser instance.
"""
short_prefix = getattr(func, 'short_prefix', '-')
long_prefix = getattr(func, 'long_prefix', '--')
attrs = {'description': func.__doc__}
for n, v in vars(func).items():
if n in valid_attrs:
attrs[n] = v
p = argparse.ArgumentParser(**attrs)
f = p.argspec = getfullargspec(func)
defaults = f.defaults or ()
n_args = len(f.args)
n_defaults = len(defaults)
alldefaults = (NONE,) * (n_args - n_defaults) + defaults
for name, default in zip(f.args, alldefaults):
a = Annotation.from_(f.annotations.get(name, ()))
if default is NONE:
dflt, metavar = None, a.metavar
else:
dflt, metavar = default, a.metavar or str(default)
if a.kind in ('option', 'flag'):
short = short_prefix + (a.abbrev or name[0])
long = long_prefix + name
elif default is NONE: # required argument
p.add_argument(name, help=a.help, type=a.type, choices=a.choices,
metavar=metavar)
else: # default argument
p.add_argument(name, nargs='?', help=a.help, default=dflt,
type=a.type, choices=a.choices, metavar=metavar)
if a.kind == 'option':
p.add_argument(short, long, help=a.help, default=dflt,
type=a.type, choices=a.choices, metavar=metavar)
elif a.kind == 'flag':
if default is not NONE:
raise TypeError('Flag %r does not want a default' % name)
p.add_argument(short, long, action='store_true', help=a.help)
if f.varargs:
a = Annotation.from_(f.annotations.get(f.varargs, ()))
p.add_argument(f.varargs, nargs='*', help=a.help, default=[],
type=a.type, metavar=a.metavar)
if f.keywords:
a = Annotation.from_(f.annotations.get(f.keywords, ()))
p.add_argument(f.keywords, nargs='*', help=a.help, default={},
type=a.type, metavar=a.metavar)
return p
def extract_kwargs(args):
arglist = []
kwargs = {}
for arg in args:
match = re.match(r'([a-zA-Z_]\w*)=', arg)
if match:
name = match.group(1)
kwargs[name] = arg[len(name)+1:]
else:
arglist.append(arg)
return arglist, kwargs
def call(func, arglist=sys.argv[1:]):
"""
Parse the given arglist by using an argparser inferred from the
annotations of the given function (the main function of the script)
and call that function with the parsed arguments. The user can
provide a custom parse_annotation hook or replace the default one.
"""
p = parser_from(func)
if p.argspec.keywords:
arglist, kwargs = extract_kwargs(arglist)
else:
kwargs = {}
argdict = vars(p.parse_args(arglist))
args = [argdict[a] for a in p.argspec.args]
varargs = argdict.get(p.argspec.varargs, [])
collision = set(p.argspec.args) & set(kwargs)
if collision:
p.error('colliding keyword arguments: %s' % ' '.join(collision))
return func(*(args + varargs), **kwargs)
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