Is it an anti-pattern in Python to define a module-level constant variable that's a string concatenation of other constant variables?

Question

At a module level, is MY_VAR_C an anti-pattern in Python 3.8+?

MY_VAR_A = "my_var_a"
MY_VAR_B = "my_var_b"
MY_VAR_C: str = MY_VAR_A + MY_VAR_B

I won't say so https://github.com/python/cpython/blob/main/Lib/string.py#L32 — azro, May 15 '22 at 14:36
@TedKleinBergman why does that example not use capital case? — user1008636, May 15 '22 at 14:40
Depends: do you use `MY_VAR_A` and `MY_VAR_B` for anything other than defining `MY_VAR_C`? — chepner, May 15 '22 at 14:40
@user1008636 What do you mean? It does use capitals in its name. — Ted Klein Bergman, May 15 '22 at 14:40
Yes, it's fine (my **opinion**, so not a good StackOverflow question). Also, If `MY_VAR_A` and `MY_VAR_B` are only used for `MY_VAR_C` or only in **that file** and nowhere else, then they should be named `_MY_VAR_A` and `_MY_VAR_B` with [leading underscores to indicate that it's sort of "private"](https://stackoverflow.com/q/1301346/1431750). Then readers (other coders) know to not use `A` and `B` in their code or imports, only to use `C`. — aneroid, May 15 '22 at 14:57

score 0 · Accepted Answer · answered May 15 '22 at 14:40

0

It is cheap and only executes once. So if it makes it easier to read it is a good trade off.

answered May 15 '22 at 14:40

MatthewMartin

1 Answers1