til/ruby/named-regex-captures-are-assigned-to-variables.md

Named Regex Captures Are Assigned To Variables

Both String and Regexp include the =~ operator as a way of checking if a string and a regex match.

When the Regexp version of =~ with named capture groups, those named captures will be auto-assigned as local variables.

Here is a regex that includes a named capture: (?<id>\d+). The parentheses define the capture area and the ?<id> specifies that whatever follows in the capture will be named id.

/Tile: (?<id>\d+)/ =~ 'Tile: 1234'
#=> 0
id
=> "1234"

After the match operator (=~) runs in the first line, the local variable id gets assigned to whatever it matches in the corresponding string.

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