Kernel#Array takes an argument and tries very hard to convert it into an Array.

Let’s look at some examples:

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Array([1,2,3])                 # => [1,2,3]
Array([])                      # => []
Array(nil)                     # => []
Array({:a => 1, :b => 2})      # => [[:a, 1], [:b, 2]]
Array(1..5)                    # => [1, 2, 3, 4, 5]

Using Kernel#Array can lead to very forgiving APIs.

Consider following method:

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def log_reading(reading_or_readings)
  readings = Array(reading_or_readings)
  readings.each do |reading|
    # A real implementation...

    puts "[READING] %3.2f" % reading.to_f
  end
end
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log_reading(3.14)
log_reading([])
log_reading([84.4, 23.8675, 33])
log_reading(nil)
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[READING] 3.14
[READING] 84.40
[READING] 23.87
[READING] 33.00

Conclusion

Kernel#Array is a go-to tool for coercing inputs into Array form.
I throw Kernel#Array and stop worrying about whether the input arrived in the expected form.