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rubysyntaxsplat

What's the feature in Ruby that allows "p *1..10" to print out the numbers 1-10?

require 'pp'

p *1..10

This prints out 1-10. Why is this so concise? And what else can you do with it?

Solution

  • It is "the splat" operator. It can be used to explode arrays and ranges and collect values during assignment.

    Here the values in an assignment are collected:

    a, *b = 1,2,3,4

=> a = 1
   b = [2,3,4]

    In this example the values in the inner array (the [3,4] one) is exploded and collected to the containing array:

    a = [1,2, *[3,4]]

=> a = [1,2,3,4]

    You can define functions that collect arguments into an array:

    def foo(*args)
  p args
end

foo(1,2,"three",4)

=> [1,2,"three",4]