Check for array not empty: any?

Question

Is it bad to check if an array is not empty by using any? method?

a = [1,2,3]

a.any?
=> true

a.clear

a.any?
=> false
<         


        

Answer 1

The difference between an array evaluating its values to true or if its empty.

The method empty? comes from the Array class
http://ruby-doc.org/core-2.0.0/Array.html#method-i-empty-3F

It's used to check if the array contains something or not. This includes things that evaluate to false, such as nil and false.

>> a = []
=> []
>> a.empty?
=> true
>> a = [nil, false]
=> [nil, false]
>> a.empty?
=> false
>> a = [nil]
=> [nil]
>> a.empty?
=> false

---

The method any? comes from the Enumerable module.
http://ruby-doc.org/core-2.0.0/Enumerable.html#method-i-any-3F

It's used to evaluate if "any" value in the array evaluates to true. Similar methods to this are none?, all? and one?, where they all just check to see how many times true could be evaluated. which has nothing to do with the count of values found in a array.

case 1

>> a = []
=> []
>> a.any?
=> false
>> a.one?
=> false
>> a.all?
=> true
>> a.none?
=> true

case 2

>> a = [nil, true]
=> [nil, true]
>> a.any?
=> true
>> a.one?
=> true
>> a.all?
=> false
>> a.none?
=> false

case 3

>> a = [true, true]
=> [true, true]
>> a.any?
=> true
>> a.one?
=> false
>> a.all?
=> true
>> a.none?
=> false