this post was submitted on 16 Mar 2026
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PEP: Is initializing typed variable with None bad practice? (lemmy.world)
submitted 2 weeks ago by AstroLightz@lemmy.world to c/python@programming.dev
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For example:

class FooBar:
    def __init__(self):
        self.a: int = None
        self.foo: str = None

Is this bad practice/go against PEP guidelines or is it fine?

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[โ€“] logging_strict@programming.dev 2 points 2 weeks ago* (last edited 2 weeks ago)

As can surmise from my handle, i'm even stricter!

Use Union, not | or Optional where ever possible.

Optional does not allow for future expansion of the typing. Optional[int] and then want to add float, so have to rewrite it Union[int, float, None] So write it with Union to begin with.

Went thru my | stage like everyone else, but grew out of it.

TypeAlias insists on Union, not |

So Union everywhere ftw

Why? If there is a possibility of making a mistake, Murphy's law dictates that it'll occur every damn time. Enough already! KISS principle is in effect.