Voici un petit quelque chose que j'ai bidouillé. Se sentir libre de suggérer des améliorations/rapports de bogues dans les commentaires:
import argparse
import ConfigParser
import os
def _identity(x):
return x
_SENTINEL = object()
class AddConfigFile(argparse.Action):
def __call__(self,parser,namespace,values,option_string=None):
# I can never remember if `values` is a list all the time or if it
# can be a scalar string; this takes care of both.
if isinstance(values,basestring):
parser.config_files.append(values)
else:
parser.config_files.extend(values)
class ArgumentConfigEnvParser(argparse.ArgumentParser):
def __init__(self,*args,**kwargs):
"""
Added 2 new keyword arguments to the ArgumentParser constructor:
config --> List of filenames to parse for config goodness
default_section --> name of the default section in the config file
"""
self.config_files = kwargs.pop('config',[]) #Must be a list
self.default_section = kwargs.pop('default_section','MAIN')
self._action_defaults = {}
argparse.ArgumentParser.__init__(self,*args,**kwargs)
def add_argument(self,*args,**kwargs):
"""
Works like `ArgumentParser.add_argument`, except that we've added an action:
config: add a config file to the parser
This also adds the ability to specify which section of the config file to pull the
data from, via the `section` keyword. This relies on the (undocumented) fact that
`ArgumentParser.add_argument` actually returns the `Action` object that it creates.
We need this to reliably get `dest` (although we could probably write a simple
function to do this for us).
"""
if 'action' in kwargs and kwargs['action'] == 'config':
kwargs['action'] = AddConfigFile
kwargs['default'] = argparse.SUPPRESS
# argparse won't know what to do with the section, so
# we'll pop it out and add it back in later.
#
# We also have to prevent argparse from doing any type conversion,
# which is done explicitly in parse_known_args.
#
# This way, we can reliably check whether argparse has replaced the default.
#
section = kwargs.pop('section', self.default_section)
type = kwargs.pop('type', _identity)
default = kwargs.pop('default', _SENTINEL)
if default is not argparse.SUPPRESS:
kwargs.update(default=_SENTINEL)
else:
kwargs.update(default=argparse.SUPPRESS)
action = argparse.ArgumentParser.add_argument(self,*args,**kwargs)
kwargs.update(section=section, type=type, default=default)
self._action_defaults[action.dest] = (args,kwargs)
return action
def parse_known_args(self,args=None, namespace=None):
# `parse_args` calls `parse_known_args`, so we should be okay with this...
ns, argv = argparse.ArgumentParser.parse_known_args(self, args=args, namespace=namespace)
config_parser = ConfigParser.SafeConfigParser()
config_files = [os.path.expanduser(os.path.expandvars(x)) for x in self.config_files]
config_parser.read(config_files)
for dest,(args,init_dict) in self._action_defaults.items():
type_converter = init_dict['type']
default = init_dict['default']
obj = default
if getattr(ns,dest,_SENTINEL) is not _SENTINEL: # found on command line
obj = getattr(ns,dest)
else: # not found on commandline
try: # get from config file
obj = config_parser.get(init_dict['section'],dest)
except (ConfigParser.NoSectionError, ConfigParser.NoOptionError): # Nope, not in config file
try: # get from environment
obj = os.environ[dest.upper()]
except KeyError:
pass
if obj is _SENTINEL:
setattr(ns,dest,None)
elif obj is argparse.SUPPRESS:
pass
else:
setattr(ns,dest,type_converter(obj))
return ns, argv
if __name__ == '__main__':
fake_config = """
[MAIN]
foo:bar
bar:1
"""
with open('_config.file','w') as fout:
fout.write(fake_config)
parser = ArgumentConfigEnvParser()
parser.add_argument('--config-file', action='config', help="location of config file")
parser.add_argument('--foo', type=str, action='store', default="grape", help="don't know what foo does ...")
parser.add_argument('--bar', type=int, default=7, action='store', help="This is an integer (I hope)")
parser.add_argument('--baz', type=float, action='store', help="This is an float(I hope)")
parser.add_argument('--qux', type=int, default='6', action='store', help="this is another int")
ns = parser.parse_args([])
parser_defaults = {'foo':"grape",'bar':7,'baz':None,'qux':6}
config_defaults = {'foo':'bar','bar':1}
env_defaults = {"baz":3.14159}
# This should be the defaults we gave the parser
print ns
assert ns.__dict__ == parser_defaults
# This should be the defaults we gave the parser + config defaults
d = parser_defaults.copy()
d.update(config_defaults)
ns = parser.parse_args(['--config-file','_config.file'])
print ns
assert ns.__dict__ == d
os.environ['BAZ'] = "3.14159"
# This should be the parser defaults + config defaults + env_defaults
d = parser_defaults.copy()
d.update(config_defaults)
d.update(env_defaults)
ns = parser.parse_args(['--config-file','_config.file'])
print ns
assert ns.__dict__ == d
# This should be the parser defaults + config defaults + env_defaults + commandline
commandline = {'foo':'3','qux':4}
d = parser_defaults.copy()
d.update(config_defaults)
d.update(env_defaults)
d.update(commandline)
ns = parser.parse_args(['--config-file','_config.file','--foo=3','--qux=4'])
print ns
assert ns.__dict__ == d
os.remove('_config.file')
TODO
Cette mise en œuvre est encore incomplète. Voici une partielle TODO liste:
Se conformer au comportement documenté
- (facile) Écrire une fonction qui détermine
dest de args en add_argument, au lieu de compter sur l' Action objet
- (trivial) Écrire un
parse_args fonction qui utilise parse_known_args. (par exemple, une copie parse_args de la cpython mise en œuvre pour garantir des appels parse_known_args.)
Moins De Choses Simples...
Je n'ai pas essayé encore. C'est peu probable mais toujours possible!-qu'il pourrait travailler...
- (difficile?) Exclusion Mutuelle
- (difficile?) Argument Groupes (Si mis en œuvre, ces groupes doivent obtenir un
section dans le fichier de configuration.)
- (difficile?) Sous-Commandes (Sous-commandes doivent également obtenir un
section dans le fichier de configuration.)
