How Can I Access Variable Values Using Their String Names in Python?

Accessing Variable Values by String Name

For many scenarios, the string-based variable lookup can be achieved using dictionaries. Here's how:

get_ext = {'text': ['txt', 'doc'],
           'audio': ['mp3', 'wav'],
           'video': ['mp4', 'mkv']}

Now, you can retrieve the desired list by the string input:

get_ext['audio']  # ['mp3', 'wav']

If you prefer using a function, you can assign the get method of the dictionary or its item fetching method (__getitem__) to it:

get_ext = get_ext.get
get_ext('video')  # ['mp4', 'mkv']

Assigning to get_ext.get provides a default behavior of returning None for unknown keys. For a KeyError instead, assign to get_ext.__getitem__.

Alternatively, you can wrap the dictionary inside a function to provide a custom default value:

def get_ext(file_type):
    types = {'text': ['txt', 'doc'],
             'audio': ['mp3', 'wav'],
             'video': ['mp4', 'mkv']}
    return types.get(file_type, [])

To optimize the setup, you can define a class with a call method to handle the lookup:

class get_ext(object):
    def __init__(self):
        self.types = {'text': ['txt', 'doc'],
                      'audio': ['mp3', 'wav'],
                      'video': ['mp4', 'mkv']}
    def __call__(self, file_type):
        return self.types.get(file_type, [])

This approach improves efficiency by creating the types dictionary only once and allows for dynamic updates:

get_ext = get_ext()
get_ext.types['binary'] = ['bin', 'exe']
get_ext('binary')  # ['bin', 'exe']

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