Checking if a variable is not nil and not zero in ruby

Question

I am using the following code to check if a variable is not nil and not zero

if(discount != nil && discount != 0) 
  .
  .
  .
end

Is there a better way to do this?

Answer 1

You could initialize discount to 0 as long as your code is guaranteed not to try and use it before it is initialized. That would remove one check I suppose, I can't think of anything else.

Answer 2

Isn't this the same question as Best ruby idiom for nil or zero?

Answer 3

You could do this:

if (!discount.nil? && !discount.zero?)

The order is important here, because if discount is nil, then it will not have a zero? method. Ruby's short-circuit evaluation should prevent it from trying to evaluate discount.zero?, however, if discount is nil.

Answer 4

unless discount.nil? || discount == 0
  # ...
end

Answer 5

unless [nil, 0].include?(discount) 
  # ...
end

Answer 6

class Object
  def nil_zero?
    self.nil? || self == 0
  end
end

# which lets you do
nil.nil_zero? # returns true
0.nil_zero?   # returns true
1.nil_zero?   # returns false
"a".nil_zero? # returns false

unless discount.nil_zero?
  # do stuff...
end

Beware of the usual disclaimers... great power/responsibility, monkey patching leading to the dark side etc.

Answer 7

if (discount||0) != 0
  #...
end

Answer 8

I believe the following is good enough for ruby code. I don't thin I could write a unit test that showed any difference between this and the original.

if discount != 0

end