Using a Python dictionary to simulate switch statement with default case-CodePudding

Is there a valid Python syntax for the following idea:

d = {_: 'value for any other key', 'x': 'value only for x key'}
value = d[key]

which should assign 'value only for x key' value ONLY when key='x'?

I have the following structure in my code, but I want to replace it with something that looks like the statements above.

if key == 'x':
  value = 'value only for x key'
else:
  value = 'value for any other key'

CodePudding user response：

I would recommend using a defaultdict from the collections module, as it avoids the need to check for membership in the dictionary using if/else or try/except:

from collections import defaultdict

d = defaultdict(lambda: 'value for any other key', {'x': 'value only for x key'})

item = 'x'
value = d[item]
print(value) # Prints 'value only for x key'

item = 'y'
value = d[item]
print(value) # Prints 'value for any other key'

CodePudding user response：

Python has match statement which is the equivalent to the C's switch statement since version 3.10, but your method may be used too:

dictionary = {
    'a': my_a_value,
    'b': my_b_value,
    '_': my_default_value
}
try:
    x = dictionary[input()]
except KeyError:
    x = dictionary['_']

CodePudding user response：

You can use dictionary's get function to customize the return value:

d = {
    'x' : 'value only for x key', 
    'y' : 'value only for y key',
    '_' : 'value for any other key'
}

key = input("Enter the key")

value = d.get(key, d['_'])

print("Value is ", value)