[ruby-core:17196] Re: Enumerable::Enumerator#with_memo

David Flanagan wrote:
>> ary.each.accumulating(0) {|i, a| a += i}
>>
>> martin
>>
>>
> 
> Martin,
> 
> The method does not work like inject: the return value of the block does 
> not become the new value of the "memo" argument.  If you try the example 
> you propose using with_memo as it is implemented now, it returns 0, not 
> the sume of the array elements. That's one reason I think that with_memo 
> is a bad name: it confuses people to think this is a variant of inject.
> I think most uses of this method will pass a mutable object as the 
> argument in order to be able to alter the value.
> 
>     David
> 

To follow-up on my previous message, perhaps the name "with_constant" or 
"with_const" would be helpful to relate this method to "with_index" and 
also to emphasize that the "memo" value passed is always the same 
object, and not the accumulated value returned by the last invocation of 
the block.

I'm beginning to feel that the method we're discussing here is one 
particular member of a set of methods for defining custom iterations. 
Imagine something like:

a1.each.with_index.and_next_of(a2).and_const(a3).and_returning([]) do
  |elt1, index, elt2, a3, retval|
end

Or:

[1,2,3].each.alternating_with([4,5,6]).and_returning([]) {|x,ret|...}

Does anyone like the use of "and" instead of "with" to indicate the 
addition of a new value to be passed to the block?

	David