Is there a better way to have this?

gistfile1.md

So recently I was looking for a way to do a comparison on a String with either another String or a Regexp. Looking online didn't yield much help, most discussions on equality focused on ==, eql?, equal?. None of which would satisfy the requirement. So I was left with this code:

def matches(compare_with)
  if compare_with.is_a?(Regexp)
    @data_string =~ compare_with
  else
    @data_string == compare_with
  end
end

Thanks to Twitter, specifically @JEG2 who completely rocks, he pointed me at ===. All of the docs on === say it is the case statement operator. In fact the String API doesn't even mention it. Looking at the Regexp API it notes it as a synonym for Regexp#=~. The thing to remember is with case:

case thing
when other_thing

The comparison are done with the when expression as the lvalue. So really, the above case statement is the same as other_thing === thing.

This means our matches method can be rewritten as:

def matches(compare_with)
  compare_with === @data_string
end

This also means it's possible to be more flexible on the match:

# @data_string = "coding for fun"
matches "oding"           # false
matches "coding for fun"  # true
matches /oding/           # true
matches String            # true

So the next time you're thinking of writing some code that needs to change based on class or how it compares with something else, think if a case statement applies. If it does, see if === works instead.