As of Python 3, you can explicitly declare variables by type:
x: int = 3
or:
def f(x: int):
return x
How would I do this with index numbers?
I am trying to maintain the address of the value without calculating the value directly…
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2What do you mean by "*index number*"? Can you provide an example? – mozway Dec 02 '21 at 01:18
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N[1] where 1 is the position (index number) of something in N – Oliver Haken Dec 02 '21 at 01:21
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Then it's an `int` – mozway Dec 02 '21 at 01:26
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The point was that x is an explicit variable… – Oliver Haken Dec 02 '21 at 01:48
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Do you mean you want to type hint the item at index `N[1]`? As in "The second item in `N` must be a string"? And what is `N`—a tuple? A list? A dictionary? These all have different considerations. – CrazyChucky Dec 04 '21 at 02:18
2 Answers
1
Type Hint doesn't raise exception when you assign incorrect type of value. It's currently only known for documentation. See in this question: https://stackoverflow.com/a/44282299/8170215
Still, if you wish to define the type hint for dictionary, you can do:
from typing import Dict
x: Dict[int, str] = {1: 'a', 2: 'b'}
which doesn't raise exception when you assign something like x = 'some string' or x['a'] = 'b'
If you want python to raise AssertionError, you can use:
# No exception
x = {1: 'a', 2: 'b'}
assert all(isinstance(key, int) for key in x)
# AssertionError
x = {'a': 'a', 2: 'b'}
assert all(isinstance(key, int) for key in x)
Or, you can use libraries like pydantic
Ming
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Is this how you want it?
x = [3]
a= x.index(3)
print (a)
which outputs 0
the int is not neccessary actually, and what is the or for?
tara
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