Ruby: You can nest regular expressions

Henning Koch

September 29, 2021Software engineer at makandra GmbH

Ruby lets you re-use existing RegExp objects by interpolating it into new patterns:

locales_pattern = /de|en|fr|es/i

html_tag_pattern = /<html lang="#{locales_pattern}">/

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Any modifiers like /i or /x will be preserved within the interpolated region, which is pretty cool. So in the example above only the interpolated locales are case-insensitive, while the pattern around it (/<html .../) remains case-sensitive.

License for source code

Posted by Henning Koch to makandra dev (2021-09-29 11:28)