常量类实例是PEP8命名约定的例外吗？

Question

If I declare an instance at the module level, which is to be set once and never changed, should I stick to uppercase naming conventions from PEP8?

Eg

entity_manager = EntityManager(config)

vs

ENTITY_MANAGER = EntityManager(config)

There is usually no discussion when the constant is a primitive type, eg an integer. But what about this?

Answer 1

The general spirit of PEP8 is to "Keep your code consistent", whether that constant is int, string, or class instance.

According to PEP8, use upper case letters separated by underscore for constants that won't be changed through out your code. That coupled with consistency , should be applied all throughout your constants, including class instances.

On using UpperCase letters :

Constants are usually defined on a module level and written in all capital letters with underscores separating words. Examples include MAX_OVERFLOW and TOTAL.

Answer 2

I agree with the general spirit of PEP8 and to keeping your code consistent. If there are issues you have with PEP8, update your .pylintrc after reaching a consensus with your team.

Regarding the original post, I also agree with the uppercase declarations of "constants," regardless of them being primitives or objects. What I disagree with, and this goes against convention, is the use of all uppercase at the module level for everything that may be immutable. Since Python does not enforce this directly, it's up to us to define naming conventions that imply both purpose and scope for developers picking up where you left off. If I don't want my "constant" to be accessible from another module, there's not much I can do in Python other than prefix with an underscore, make lowercase, or obfuscate the name in some way.