to_s

        # Regexp.to_s

(from ruby core)
---
    rxp.to_s   -> str

---

Returns a string containing the regular expression and its options
(using the `(?opts:source)` notation. This string can be fed back in to
Regexp::new to a regular expression with the same semantics as the
original. (However, `Regexp#==` may not return true when comparing the
two, as the source of the regular expression itself may differ, as the
example shows).  Regexp#inspect produces a generally more readable
version of *rxp*.

    r1 = /ab+c/ix           #=> /ab+c/ix
    s1 = r1.to_s            #=> "(?ix-m:ab+c)"
    r2 = Regexp.new(s1)     #=> /(?ix-m:ab+c)/
    r1 == r2                #=> false
    r1.source               #=> "ab+c"
    r2.source               #=> "(?ix-m:ab+c)"