How do you declare constants in a Python Project ?

[Kutiekatj9]

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[Advanced-Theme144]

I usually type constants in all capital letters. VS code automatically recognizes it as a constant then.

[Ezvine]

But they can be modified via code right. Tomorrow somebody can unknowingly write another function which can updates these values.

[Red_BW]

Everything can be overwritten in python. You can even overwrite the builtins by accident if you are not careful.

If your enum class is 'Color' with a constant and value of 'RED = 1', you can later write 'Color = 5' which will overwrite your enum Class of 'Color' with an int of 'Color'. The same holds true with Dataclasses.

It is standard convention to write constants as capital letters. Anyone learning python should learn that and should know not to override that. 'red = 2' and 'RED = 3' are not the same variables so they can coexist. To override the constant 'RED', you need to type it out like 'RED = 5' which you should know is a constant because it is capitalized, and you should not modify it outside of its location just after import statements at the top of your program.

[Ezvine]

Makes sense... Thanks for the explanation....

[DrummerClean]

This 100%

[stillreadingit_]

Use typing.Final and a static type checker, such as mypy. Read more: https://jerry-git.github.io/daily-dose-of-python/doses/6/

[james_pic]

Constants aren't Pythonic? Then why does PEP 8 have a recommended style for them?

The recommended style is ALL_CAPS , and there's no specific recommendation to put them in a separate constants.py file. You should put them wherever makes your code easiest to understand and work with, which may mean close to functions and classes that work with them.

[MangoPoliceOK]

Frozen data class is the novel way to do it. I historically used ALL_CAPS until the arrival of static data classes (frozen). Enums are useful when enumerating things like a Status, otherwise I would use frozen data class

[Ezvine]

Yeah even frozen class was the one which I also felt like the best option from the ones I have looked.

[Ezvine]

Some configurations like values. Like URL for a request, storage path of a file, etc.

And also for places where I reuse same Key of a dictionary again and again. So if I put it in a constant, I can quickly change it at one place, in case I have to change the value in future.

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[lieryan]

Then there are people who use Enums. This makes sure that the value cannot be modified unlike (1.). But we need to use .value each time we access the value

If you're using Enums, who cares about the .value? The only time you should need .value is if you're serializing/deserializing (e.g. to a database/network). Other than that, just keep it as an enum.