Error: undeclared field: 'captures' for type nre.RegexMatch

Question

I'm trying to match a given string with nre:

from nre import findIter, re

const sourceString = """
39
00:04:01,116 --> 00:04:01,783
Attrape.
"""
let srtRex = re"\d+\R\d+:\d+:\d+,\d+ --> \d+:\d+:\d+,\d+\R(\w+)"

for m in findIter(sourceString, srtRex, 0):
  echo(m.captures[0])

This doesn't compile though, it fails with Error: undeclared field: 'captures' for type nre.RegexMatch [declared in /usr/local/Cellar/nim/1.2.6/nim/lib/impure/nre.nim(149, 3)].

This is weird, because if I do echo(m), I get the raw strings, so the match itself worked fine. It's only this field I can't access. And that is weird, because in this issue the (working) example code is pretty much the same.

Answer 1

Importing whole modules is idiomatic in Nim, and leads to ambiguities rarely, thanks to a strong type system. see https://narimiran.github.io/2019/07/01/nim-import.html for a great rundown on why Nim doesn't share Python's import issues.

However, here's how to do what you want to do, even if it's not idiomatic Nim:

You're using more than just re and findIter, you also use the proc captures, and the [] proc, so your import line needs to be:

from nre import findIter, re, captures, `[]`

or, for complete namespace separation, but quite ugly, you can:

from nre import nil
let srtRex = nre.re"\d+\R\d+:\d+:\d+,\d+ --> \d+:\d+:\d+,\d+\R(\w+)"

for m in nre.findIter(sourceString, srtRex, 0):
  echo(nre.`[]`(nre.captures(m),0))

Answer 2

It seems to be the imports. It works with import nre instead of from nre import findIter, re. But why? I want to keep my namespace clean!