How Can I Access a Predefined List Based on a String Input in Python?

Accessing Variables by String Name

Problem:

You desire a function that returns a predefined list based on a string input. For instance, given a string "audio," the function should output the list ['mp3', 'wav'].

Easiest Solution with a Dictionary:

A standard dictionary can fulfill this requirement effortlessly.

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

get_ext['video']  # Returns ['mp4', 'mkv']

Using Functions:

For more advanced applications, utilizing functions might be preferred.

Assigning a Dictionary's Get Method:

get_ext = get_ext.get

get_ext('video')  # Returns ['mp4', 'mkv']

Wrapping a Dictionary Inside a Function:

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

    return types.get(file_type, [])

Creating a Custom Class for Extensibility:

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, [])

get_ext = get_ext()

get_ext('audio')  # Returns ['mp3', 'wav']

This allows you to modify file types dynamically.

get_ext.types['binary'] = ['bin', 'exe']

get_ext('binary')  # Returns ['bin', 'exe']

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