如何使用 function 调用列表中的 function arguments

Question

I want to do something like this

allowed_args = ['--email', '--password', '--verbose']

if '--email' in allowed_args:
    parser.add_argument('--email')
if '--password' in allowed_args:
    parser.add_argument('--password', help='Better dont use your password on command line')
if '--verbose' in allowed_args:
    parser.add_argument('--verbose', action='store_true')

Because I will need to define, which arguments are allowed before parsing the arguments using argparse .

This works like expeted, but how can I avoid, using these repetitive if clauses (this is just an example, I would actually have a lot more...)? I would like somehow to predefine the arguments and then choose which of them to use.

Answer 1

This is a little tricky:

allowed_args = {
    '--email':{}, 
    '--password':{'help':'Better dont ...',}, # you can add more items
    '--verbose':{'action':'store_true',}
}

then:

for k,v in allowed_args.items():
    parser.add_argument(k, **v)

You can add as many as arguments to your allowed_args values( the dict inside ).

Answer 2

You could write that like this:

for name, args, kwargs in \
    [('--email', [], {}),
     ('--password', [], {help: 'Better dont use your password on command line'}),
     ('--verbose', [], {action: 'store_true'})]:

    parser.add_argument(name, *args, **kwargs)

The mapping could also be stored in a dictionary, but by using a list of tuples, this ensures that options are added in the desired order even if used on older versions of Python.

Answer 3

You can define a dictionary of args and kwargs to pass in the event of a match:

parameters = {
     "--email": {
         "args": [],
         "kwargs": {},
     },
     "--password": {
         "args": [],
         "kwargs": {
             "help": "Better dont use your password on command line"
         },
     },
     "--verbose": {
         "args": [],
         "kwargs": {
             "action": "store_true"
         }
     }
}

Then, you can iterate over your input array and add the parameters in a loop:

allowed_args = ['--email', '--password', '--verbose']
for arg in allowed_rags:
    arg_parameters = parameters[arg]
    parser.add_argument(arg, *arg_parameters['args'], **arg_parameters['kwargs'])

You could also check whether the given parameter exists and raise an exception:

    allowed_args = ['--email', '--password', '--verbose']
    for arg in allowed_rags:
        if arg not in parameters:
            raise NotImplementedError(arg)
        arg_parameters = parameters[arg]

Furthermore, if you use a set as input, you could avoid some edge cases:

allowed_args = {'--email', '--password', '--verbose'}
for arg in allowed_args & parameters:
    arg_parameters = parameters[arg]
    parser.add_argument(arg, *arg_parameters['args'], **arg_parameters['kwargs'])