Last Updated: February 25, 2016

Enumerable ranges from strings in Ruby

A snippet that I find myself using quite a bit. This monkey-patches the String class with a to_r method, giving you a Range that can be called with enumerators. Since this uses eval, it accepts numbers only for security.

class String
 def to_r
 a = self.partition(/\(.*?\)/)
 fail "No range in string" if a[0].empty?
 fail "Invalid range #{a}" if a.select { |v| v.match(/[A-Za-z]/) }
 eval a[1]
 end

 def to_r_leading_zero
 a = self.partition(/\(.*?\)/)
 fail "No range in string" if a[0].empty?
 fail "Invalid range #{a}" if a.select { |v| v.match(/[A-Za-z]/) }
 r = eval a[1]
 if r.first.to_s.size == 1
 eval "\'#{"0" + r.first.to_s}\'..\'#{r.last.to_s}\'"
 end
 end
end

#ruby

#patch

#string

#range