Are iterators fundamentally flawed ?

re: Are iterators fundamentally flawed ?

Tetsuo — Tue, 05 Aug 2008 22:00:21 GMT

Iterators, objects and threads are not broken or flawed. They just weren't designed to be optimal in a parallel processing environment.

OO languages (at least mainstream ones) pass object references, objects have state, and are mutable 'by default' (in contrast of pass-by-copy semantics in Pascal or C, in which even if you can change a struct property, it won't reflect onto the original one). STATE is what makes difficult programming in a multi-core environment, not common constructs in mainstream languages.

And that is what makes languages like Scala, which uses the concept of Actors and message-passing, more multi-core-friendly, not closures.

re: Are iterators fundamentally flawed ?

Markus Kohler — Tue, 05 Aug 2008 13:26:55 GMT

Hi,

I agree iterators are somehow flawed.

They are used because writing control flow operations cannot be done properly in languages that do not support closures.

Fortunately support for closures fixes is under way in most major programming languages.

Regards,

Markus

re: Are iterators fundamentally flawed ?

bill — Tue, 05 Aug 2008 09:33:14 GMT

Hi Granville,

I haven't looked at it yet either. I suspect they would call GetEnumerator, and then work with the enumerator, sharing that across threads. that'd of course be contrary to using the language constructs in C# ;)

re: Are iterators fundamentally flawed ?

Granville Barnett — Sat, 02 Aug 2008 16:29:50 GMT

In Thread Building Blocks (TBB, by Intel for C++) you can use iterators to tell TBB how to split something up.

I've not looked at it yet, but have you looked at the TPL and its classes using Reflector? It might shed some light on the subject.