Regex "is not a constant" compilation error
This happens when you're trying to assign to a constant that has a type that can't be constant (like for example, Regexp
). Only basic types likes int
, string
, etc. can be constant. See here for more details.
Example:
pattern = regexp.MustCompile(`^[A-Za-z0-9_\.]+`)
// which translates to:
const pattern = regexp.MustCompile(`^[A-Za-z0-9_\.]+`)
You have to declare it as a var
for it to work:
var pattern = regexp.MustCompile(`^[A-Za-z0-9_\.]+`)
In addition, I usually put a note to say that the variable is treated as a constant:
var /* const */ pattern = regexp.MustCompile(`^[A-Za-z0-9_\.]+`)
The error is pretty clear. If you are trying to do this globally...
Don't do:
const pattern = regexp.MustCompile(`^[A-Za-z0-9_\.]+`)
Instead do:
var pattern = regexp.MustCompile(`^[A-Za-z0-9_\.]+`)
Or if you really want the pattern in a constant:
const pattern = `^[A-Za-z0-9_\.]+`
var alphaNum = regexp.MustCompile(pattern)