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Ruby

Posted by Joshua Shroy
Joshua Shroy
9,943 Points

Unfamiliar use of symbol with operator.

I ran across a line of code with an unfamiliar symbol/operator - (:*)

Here it is in context:

(1..num).inject(:*) || 1

I understand the output returns a factorial, but can anyone explain the colon's function and relation to the multiply operator?

1 Answer

Sam Shiffman
Sam Shiffman
7,466 Points
Sam Shiffman
Sam Shiffman
7,466 Points

The colon ":" tells Ruby to apply the subsequent operator (i.e. use it as a method) to the successive elements of the collection created/built by the #inject (aka #reduce) method. So the given snippet of code is a shorthand form (aka syntactic sugar) of the following:

(1..num).inject { |product, factor| product * factor } || 1

Start an irb session in your Terminal and try it. You should get the same answer using either form.