Check if a constant is already defined

Question

This is a simple one, I hope. How do I check, in the following example, if a constant is already defined?

#this works var = var||1 puts var var = var||2 puts var  #this doesn't CONST = CONST||1 puts CONST CONST = CONST||2 puts CONST  => 1    1    uninitialized constant CONST (NameError) 

Answer 1

CONST = 2 unless defined? CONST 

See here for more about awesome defined? operator.

^{P.S. And in the future I guess you'll want var ||= 1 instead of var = var||1.}

Answer 2

const_defined? API

pry> User.const_defined?("PER_PAGE") => true pry> User.const_defined?("PER_PAGE123") => false