Regex with named capture groups getting all matches in Ruby

Named captures are suitable only for one matching result.
Ruby’s analogue of findall is String#scan. You can either use scan result as an array, or pass a block to it:

irb> s = "123--abc,123--abc,123--abc"
=> "123--abc,123--abc,123--abc"

irb> s.scan(/(\d*)--([a-z]*)/)
=> [["123", "abc"], ["123", "abc"], ["123", "abc"]]

irb> s.scan(/(\d*)--([a-z]*)/) do |number, chars|
irb*     p [number,chars]
irb> end
["123", "abc"]
["123", "abc"]
["123", "abc"]
=> "123--abc,123--abc,123--abc"