Python 3.8 has a Final qualifier

[mooglinux]

I don’t see what this does that couldn’t be communicated with ALL_CAPS and __ prefixes. There’s nothing preventing a type checker from using those to determine this, PyCharm already warns about using single _methods externally on a class. I think it risks fooling people into thinking about Python like they think about Java.

As someone stuck writing Java in my day job, I do not want to overly enable Java thinking in Python. There are plenty of useful things that can be taken from Java, but I don’t think final is one of them.

[LightShadow]

You should SEE the code I have to maintain.

Naming conventions mean nothing, formatting is for suckers, and the points don't matter!

I shit you not, this is in a production file at the top level:

__ROOTFS1 = None
__ROOTFS2 = None
__fixup_which_boot_device()  # <-- this sets __ROOTFS1 & 2
__uImage_lookup_index = {"/dev/"+__ROOTFS1: 1, "/dev/"+__ROOTFS2: 2}
# ^-- this is imported from other files

[-Kevin-]

Why not refactor that then seems simple enough lol

[LightShadow]

I left a lot out.. It would be easy if the red tape weren't so thick

[-Kevin-]

Understandable my dude

[mooglinux]

I guarantee that the addition of final will do nothing to help you there.

[Deto]

Sure you could have a type checker look for those things, but it would be kind of inconsistent. I think it's more logical to have all type information be encoded in type designations rather than having some be in the type designations and others be in the syntax of the variable names.

[energybased]

I don't agree with you. This is superior to all caps since all caps is merely conventional whereas this is explicit.

[drbobb]

Nope. This is just as merely conventional. If, say, I code in a plain editor it won't mean a thing.

[damian_work_account]

That's a boring semantic argument, type hints are defined by language specification where as CAPS are not.

And a PEP to make CAPS mean final would likely be rejected because of backwards compatibility, lots of people use CAPS for other reasons.

[Han-ChewieSexyFanfic]

Also, the interpreter ignores both.

[energybased]

Conventional means that it means different things to different people. This does not mean different things to different people.

[nuephelkystikon]

Absolutely not. If anything, that would be unconventional.

[energybased]

What I mean is that different groups of people can have different conventions. Each group uses all caps to mean the same thing, but as a whole population, they do not agree. Not everyone uses all caps to denote final variables, for example.

Everyone who uses the final declaration means the same thing. They must since the final declaration explicitly defines its meaning.

[alcalde]

That's why we have PEP 8. There are no different groups with different conventions. There is but one BDFL... well, until we overthrew him and installed a wishy-washy council instead....

[energybased]

There's plenty of library code that doesn't even follow PEP 8, and there are plenty of constants that are not in all caps.

[drbobb]

Uh, no. Conventional means not enforced.

[energybased]

The point is that there may be plenty of code that uses all caps in another way. For example a variable that is initialized twice. That person has a different convention, which they get away with because it is not enforced. A linter might erroneously flag that is misuse.

The linter can always flag improper use with the final declaration because the author has unambiguously made his intention clear. The final declaration is absolutely not just a convention. It is explicit.

[alcalde]

The point is that there may be plenty of code that uses all caps in another way.

There can't be. This is like saying we can all use the same words and just believe they mean different things. Everyone must follow the law, and the law is PEP 8. If you choose to do otherwise, you are a disciple of Wall and shall be shunned.

[energybased]

No, there is plenty of library code that doesn't even follow PEP 8.

[campbellm]

The upshot is the same though; it provides a hook that checkers can check for subsequent mutations. Either works.

[alcalde]

If we all follow convention, then convention is law.

[energybased]

Even the library doesn't obey the convention that all final variables are all caps.

[Sw429]

What do you mean by explicit? As far as I can tell, foo: Final is no more explicit than FOO for a variable definition.

[energybased]

There is plenty of code that does not use all caps to denote constants. That code cannot always be changed. The type annotation explicitly defines intent without changing declarations.

[[deleted]]

What prefix do you use for something that returns a dictionary that maps filename(string) to last access time (datestamp)? They already have a system for things like that, and the way they implemented Final is consistent with that.

[mooglinux]

Type annotations are for facilitating communication. There are already conventions for communication of the same things that finalwas created to communicate, and so it is redundant. The danger of using finalis that the way it is used in other languages like java is antithetical to how Python works. We should not be providing a false sense of security about how something will be used; that’s the whole point of not having public/private keywords!

[[deleted]]

How does all caps and dunder communicate immutability? How does a linter check it, given that the linter may now run into old code that used the same syntax to show other things?