Replace regex with pattern as string to support OTP 28

[TBK145]

OTP 28 changes the implementation of the regex module, and as a result you can no longer use regexes as module attributes.

By changing the regex to a pattern as a string it can still be used in the error message, and just needs to be compiled before usage.

[benwilson512]

Hey @TBK145 is there some Elixir issue tracking this? Recompiling the regex on every function call is going to be much worse for performance.

[josevalim]

Suggested change

@valid_name_regex "^[_A-Za-z][_0-9A-Za-z]*$"

[josevalim]

Suggested change

	@valid_name_regex
	|> Regex.compile!()
	|> Regex.match?(name)
	Regex.match?(~r/^[_A-Za-z][_0-9A-Za-z]*$/, name)

[josevalim]

This is a change on Erlang/OTP 28, we can no longer precompile them in the module body, but we only need to move it inside. Elixir v1.19 will emit a warning telling you to do exactly that.

[TBK145]

Hi @josevalim , at first I wanted to solve it in the way you propose, but the regex is also referenced here, so I did it in this way to only have to maintain the regex in one place.
But I understand it's better to maintain the regex twice in favour of performance, thanks @benwilson512 I did not think about that.

[josevalim]

In this case it is best to move the regex to a private function and reuse it. :)

[TBK145]

That was actually the first thing I tried, but since it's a module attribute, the function is not defined yet before calling.
I could move the whole @description block into the function, but I don't know if that has any negative side-effects.

[josevalim]

What I mean is this:

defp valid_regex_name, do: ~r/foobar/

And use it as valid_regex_name().

[TBK145]

I understand, but what I mean is that the regex is also used in module attribute @description, which cannot call a function from that same module.

[josevalim]

You can also move it to a function. I assume there isn't much benefit for those being attributes anyway, besides user convenience.

[benwilson512]

Thank you @josevalim for the assist!