Question

We can create, for example, new array following way:

values = Array.new(5) { rand(6) + 1 } # [3, 2, 3, 3, 2]

But how does it work in terms of function arguments?

For example if I define some function:

def some_func(a, b, c)
end

Function is defined with 3 arguments, I can make some of them optional but either way to call this function I would use

some_func(value1)
some_func(value1, value2)
some_func(value1, value2, value3)

But it doesn’t make sense to me in case of Array, where this block to define values go?

5 is definitely argument to a new function but what about block?

Thank you.

Answer 1

Passing a block to Array.new works the same way as passing a block to any other method: It’s a sort of implicit argument. It does not appear in the method’s argument list (unless you “reify” it into a Proc using &), but you can call it using yield and check whether it is there using block_given?.

For example if your some_func method were to take a block, it could look like this:

def some_func(a,b,c)
  if block_given?
    yield a+b+c
  else
    a+b+c
  end
end

some_func(1,2,3) #=> 6
some_func(1,2,3) {|x| x*2} #=> 12