What does the * (star) mean in Ruby?

ruby splat
Ernest picture Ernest · Nov 13, 2010 · Viewed 22.8k times · Source

Possible Duplicate:
What is the * operator doing to this string in Ruby

Probably there is answer for that elsewhere, but I just don't know how to find it...

If I am right, the * means multiple parameters if used in function definition:

def hero(name, *super_powers)

But what does * do in the code like this:

Hash[*[[:first_name, 'Shane'], [:last_name, 'Harvie']].flatten] # => {:first_name=>"Shane", :last_name=>"Harvie"}

Answer

osgx picture osgx · Nov 13, 2010

Variable Length Argument List, Asterisk Operator

The last parameter of a method may be preceded by an asterisk(*), which is sometimes called the 'splat' operator. This indicates that more parameters may be passed to the function. Those parameters are collected up and an array is created.

The asterisk operator may also precede an Array argument in a method call. In this case the Array will be expanded and the values passed in as if they were separated by commas.

Related questions

What does a double * (splat) operator do

Have you seen a function declared like this? def foo a, **b ... end I understand that a single * is the splat operator. What does ** mean?

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

Given the Ruby code line = "first_name=mickey;last_name=mouse;country=usa" record = Hash[*line.split(/=|;/)] I understand everything in the second line apart from the * operator - what is it doing and where is the documentation for this? (…

Read More
Hash Destructuring

You can destructure an array by using the splat operator. def foo(arg1, arg2, arg3) #...Do Stuff... end array = ['arg2', 'arg3'] foo('arg1', *array) But is there a way to destruct a hash for option type goodness? …

Read More