Add support for changing global variables in versions

[zmievsa]

Is your feature request related to a problem? Please describe.
Often things like error messages and status codes are also versioned. We want some solution that allows us to change any variables in-between API versions.

Describe the solution you'd like
I'm thinking of the following interface:

from cadwyn.structure import module

module(latest.my_module).variable("some_variable").had(value="'hello darkness'", annotation="str")

which will generate the following code:

# within latest.my_module

some_variable: str = 'hello darkness'

Do we really need this though? I am worried that this might be an overkill that will add hidden side effects.

For the sake of simplicity, we won't allow defining variables in-between versions — only changing their values and annotations.

[m0n0x41d]

I am taking it

[zmievsa]

I thought about it once again: this is a bad idea. Instead, if-statements with side effects are a much safer choice.

This functionality would render side effect detection useless and will significantly complicate tests of business code so its value is not enough to justify its complexity.