Function rb_enum_values_pack 

pub unsafe extern "C" fn rb_enum_values_pack(
    argc: c_int,
    argv: *const VALUE,
) -> VALUE

Basically identical to [rb_ary_new_form_values], except it returns something different when argc < 2.

@param[in] argc Number of objects of argv. @param[in] argv Arbitrary objects. @retval RUBY_Qnil argc is zero. @retval argv[0] argc is one. @retval otherwise Otherwise.

@internal

What is this business? Well, this function is about yield’s taking multiple values. Consider following user-defined class:

class Foo
  include Enumerable

  def each
    yield :q, :w, :e, :r
  end
end

Foo.new.each_with_object([]) do |i, j|
  j << i                      # ^^^ <- What to expect for `i`?
end

Here, Foo#each_with_object is in fact Enumerable#each_with_object, which doesn’t know what would be yielded. Yet, it has to take a block of arity 2. This function is used here, to “pack” arbitrary number of yielded objects into one.

If people want to implement their own Enumerable#each_with_object this API can be handy. Though @shyouhei suspects it is relatively rare for 3rd party extension libraries to have such things. Also Enumerable#each_entry is basically this function exposed as a Ruby method.

Generated by rb-sys for Ruby mri-x86_64-linux-gnu-3.2.3