How to check if a Ruby object is a Boolean
Solution 1:
Simplest way I can think of:
# checking whether foo is a boolean
!!foo == foo
Solution 2:
I find this to be concise and self-documenting:
[true, false].include? foo
If using Rails or ActiveSupport, you can even do a direct query using in?
foo.in? [true, false]
Checking against all possible values isn't something I'd recommend for floats, but feasible when there are only two possible values!