Python方便地将字典参数传递给函数

Question

I thought about attaching the dictionary to the local scope somehow, however I have seen similar questions asked on SO - usually with the response 'don't do it!'. I will illustrate my problem and welcome any suggestions to overcome this.

If have an options dictionary (read from JSON so prefer not to have to mess to much with it) and I have decided to pass this as follows;

def testParse(dataObj, userOptions):

    # Merge default with passed options taking prescidence
    defaultOpts = {

        'boxheight' : 200,
        'boxwidth'  : 100,
        'padding'   : 150

    }
    opt = dict(userOptions.items() | defaultOpts.items())

The question is; Is there any way to attach each value in the dictionary to the local scope using the key so that rather than copying out the entire dictionary

boxheight = opt['boxheight']

etc., or writing opt['boxheight'] every time I refer to it. Can I just loop the opt dictionary and assign the value programatically?

I am in no way attached to the approach outlined, but all options will be used in local expressions at some point and they exist from the outset as a dictionary. Many thanks in advance for your suggestions.

[Disclaimer: Only been working with Python for a few days]

Answer 1

Ok, thanks to @jonrshapre's comment I have the following solution

# user options
userOps = { 'name' : 'joe', 'age' : 21 }
data = (1,2)

# default options specified as function argument
def _func(data, name, lovesSO = True, **kwargs):

    print(data)
    print(name)
    print(lovesSO)
    print(kwargs)

# Call
_func(data, **userOps)    

# OUTPUTS
# (1,2)
# joe
# True
# {'age' : 21}

The price to pay with this approach appears to be the slightly unconventional calling syntax (although as pointed out in the comments this is only unusual to a newbee like me). However this can be fixed up by defining

def func(data, options): _func(data, **options)

Or another solution based upon @ Sven Marnach's comment;

# Utility options class
class Options:
    def __init__(self, defaults, user_opts):
        vars(self).update(defaults)
        vars(self).update(user_opts)

def func2(data, userOps):

    opt = Options({ 'lovesSO' : True}, userOps)

    print(data)
    print(opt.name)
    print(opt.lovesSO)

# Call    
func2(data, userOps)

# OUTPUT
# (1, 2)
# joe
# True

This has the drawback of defining a helper class but has the benefit of clearly knowing which variables are user definable options by the presence of the opt. prefix. In addition the calling syntax is natural.

In both cases, unused user options are stored as either the kwargs dictionary (in the first case) or as unused entries in the opt dictionary.

Personally I have decided to opt for the second solution.