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 the

Answer 1

You can take advantage of the NilClass provided #to_i method, which will return zero for nil values:

unless discount.to_i.zero?
  # Code here
end

If discount can be fractional numbers, you can use #to_f instead, to prevent the number from being rounded to zero.

Answer 2

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 3

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 4

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 5

ok, after 5 years have passed....

if discount.try :nonzero?
  ...
end

It's important to note that try is defined in the ActiveSupport gem, so it is not available in plain ruby.

Answer 6

You can convert your empty row to integer value and check zero?.

"".to_i.zero? => true
nil.to_i.zero? => true