Method: Enumerator#initialize

Defined in:
enumerator.c

#new(size = nil) {|yielder| ... } ⇒ Object

Creates a new Enumerator object, which can be used as an Enumerable.

Iteration is defined by the given block, in which a “yielder” object, given as block parameter, can be used to yield a value by calling the yield method (aliased as <<):

fib = Enumerator.new do |y|
  a = b = 1
  loop do
    y << a
    a, b = b, a + b
  end
end

fib.take(10) # => [1, 1, 2, 3, 5, 8, 13, 21, 34, 55]

The optional parameter can be used to specify how to calculate the size in a lazy fashion (see Enumerator#size). It can either be a value or a callable object.

Yields:

  • (yielder) 

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# File 'enumerator.c', line 478

static VALUE
enumerator_initialize(int argc, VALUE *argv, VALUE obj)
{
    VALUE iter = rb_block_proc();
    VALUE recv = generator_init(generator_allocate(rb_cGenerator), iter);
    VALUE arg0 = rb_check_arity(argc, 0, 1) ? argv[0] : Qnil;
    VALUE size = convert_to_feasible_size_value(arg0);

    return enumerator_init(obj, recv, sym_each, 0, 0, 0, size, false);
}