Ruby: Map a function over something if array, do it once if a single object

Question

I'm currently doing this for one of my functions in Ruby:

if @to_pass.kind_of?(Array)
        @to_pass.map do {|item| do_a_function(item)}
    else
        do_a_function(item)
    end

Is there a shorter way of doing "if this is an array, map over and apply the function, if not, then do the function"?

Answer 1

You can just convert a single object into an array. If you are not using the output, each would be better than map as it would not create a new array.

# if single object doesn't respond to to_a
# as Guilherme Bernal pointed out in comments, flatten(1) should be used rather than flatten
[@to_pass].flatten(1).each {|item| do_a_function(item) }

# if it does
@to_pass.to_a.each {|item| do_a_function(item) }

Answer 2

只需使用Array方法，该方法将创建一个包含单个项目的数组，或者仅返回原始数组。

Array(@to_pass).map { |item| do_a_function(item) }

Answer 3

You could transform always to array and make use of flatten, like this:

([@to_pass].flatten).map { |item| do_a_function(item) }

This works because flatten will keep already flattened arrays as they are.

Answer 4

I'd use this:

[*@to_pass].map{ |e|
  ...
}

If @to_pass is a single element or an array it will be converted to an array.