What does the (unary) * operator do in this Ruby code?

Question

Given the Ruby code

line = \"first_name=mickey;last_name=mouse;country=usa\" 
record = Hash[*line.split(/=|;/)] 

I understand everything i

Answer 1

The splat operator unpacks an array passed to a function so that each element is sent to the function as an individual parameter.

A simple example:

>> def func(a, b, c)
>>   puts a, b, c
>> end
=> nil

>> func(1, 2, 3)  #we can call func with three parameters
1
2
3
=> nil

>> list = [1, 2, 3]
=> [1, 2, 3]

>> func(list) #We CAN'T call func with an array, even though it has three objects
ArgumentError: wrong number of arguments (1 for 3)
    from (irb):12:in 'func'
    from (irb):12

>> func(*list) #But we CAN call func with an unpacked array.
1
2
3
=> nil

That's it!