# [RFC] Iteration tools - Thread: https://externals.io/message/41624 - Original archive: https://news-web.php.net/php.internals/41624 - Started by Ionut Gabriel Stan on 2008-11-03T15:07:14+00:00 - Messages: 6 - Reply by email to internals@lists.php.net - More for agents: search with https://externals.io/search.md?q={query} · JSON API at https://externals.io/api · documentation at https://externals.io/llms.txt --- ## #41624 — Ionut Gabriel Stan — 2008-11-03T15:07:14+00:00 URL: https://externals.io/message/41624#41624 Hello everybody, As a result of the advice given in the thread "array_key_exists BC break", I have written an RFC concerning some higher order functions that, I believe, could a helpful addition to the language. Please note that I'm a userland developer and have no clue about PHP internals so please forgive any stupidities I might have said in the RFC and make the appropriate corrections. That also means that, if positive feedback is received, this RFC needs a developer with PHP internals knowledge to implement it. The RFC can be found here: http://wiki.php.net/rfc/iteration-tools Hoping that I've made sense in what I wrote there, please feel free to comment as you like. Regards, Ionut --- ## #41625 — Marcus Boerger — 2008-11-03T15:41:29+00:00 URL: https://externals.io/message/41624#41625 · In reply to: #41624 Hello Ionut, some remarks about your proposal: 1) You can turn any array into a Traversable using (Recursive)ArrayIterator. Though this solution is still slow. The issue is that the c-level code needs to verify the current pointer every single time it uses it and that means traversing the array from the beginning. That said we might want to: a) Optimize that for cases where we don't have to. Basically when nothing else is pointing to the array (refcount==1) we know when the array can be changed and do not have to verify it always. b) provide a lower level array to traversable mechanism that operates on the current pointer provided by the array itself. That way having no need to verify that pointer at all. 2) Ther are `iterator_apply()`, `iterator_to_array()`, `iterator_count()` The first can be used for a lot of the things you were looking for, especially when used together with lambdas. Also not that you can use it to pass the iterator itself to the function being called easily. Still a few of the things you mention can be implemented faster in the same way `iterator_apply()` was done. In fact the code can be based on the lovel c-implementation provided. marcus Monday, November 3, 2008, 4:07:14 PM, you wrote: > Hello everybody, > As a result of the advice given in the thread "array_key_exists BC > break", I have written an > RFC concerning some higher order functions that, I believe, could a > helpful addition to the language. > Please note that I'm a userland developer and have no clue about PHP > internals so please > forgive any stupidities I might have said in the RFC and make the > appropriate corrections. > That also means that, if positive feedback is received, this RFC needs a > developer with PHP > internals knowledge to implement it. > The RFC can be found here: http://wiki.php.net/rfc/iteration-tools > Hoping that I've made sense in what I wrote there, please feel free to > comment as you like. > Regards, > Ionut Best regards, Marcus --- ## #41633 — Ionut Gabriel Stan — 2008-11-04T09:11:08+00:00 URL: https://externals.io/message/41624#41633 · In reply to: #41625 > Hello Ionut, > > some remarks about your proposal: > > 1) You can turn any array into a Traversable using > (Recursive)ArrayIterator. Though this solution is still slow. The issue is > that the c-level code needs to verify the current pointer every single time > it uses it and that means traversing the array from the beginning. That > said we might want to: > a) Optimize that for cases where we don't have to. Basically when nothing > else is pointing to the array (refcount==1) we know when the array can be > changed and do not have to verify it always. > b) provide a lower level array to traversable mechanism that operates on > the current pointer provided by the array itself. That way having no need > to verify that pointer at all. > > 2) Ther are `iterator_apply()`, `iterator_to_array()`, `iterator_count()` > The first can be used for a lot of the things you were looking for, > especially when used together with lambdas. Also not that you can use it to > pass the iterator itself to the function being called easily. > > Still a few of the things you mention can be implemented faster in the same > way `iterator_apply()` was done. In fact the code can be based on the lovel > c-implementation provided. > > marcus > > Monday, November 3, 2008, 4:07:14 PM, you wrote: > > > > […] > > > > […] > > > > […] > > > > […] > > > > […] > > > > […] > > > > > > Best regards, > Marcus > > > Hi Marcus, Thanks for your answer. I had no idea there is an `iterator_apply()` function, I did a little bit of search after you mentioned it and found it nowhere in the docs but apparently it is present in my 5.2.6 installation. `iterator_to_array()` and interator_count() are very useful functions which I had knowledge of but forgot about them in my wiki. I recognize that my proposal can easily be implemented in userland code with the classes and functions that we already have, as you mentioned already. The only real advantage is the speed given by the C level code and a common, standard API for array and Traversables. This way `array_map()`, `array_reduce()` and the like could be deprecated. I always have to look in the docs or pay a little attention to my IDE to see what param goes where. Anyway, I see there's nobody else that would like this but it's ok, at least now we have namespaces so that I don't have to come up with ugly names like my_map() for these kind of helper functions. Cheers, Ionut --- ## #41634 — troels knak-nielsen — 2008-11-04T09:39:51+00:00 URL: https://externals.io/message/41624#41634 · In reply to: #41633 On Tue, Nov 4, 2008 at 10:11 AM, Ionut Gabriel Stan wrote: > Anyway, I see there's nobody else that would like this but it's ok, at least > now we have namespaces so that > I don't have to come up with ugly names like my_map() for these kind of > helper functions. I like the proposal. With the advent of first-class functions, functional-style iteration is becoming possible. An abstraction that hides away the difference between arrays and traversables would help further in this direction. And this is something that is much better implemented in the language, than in userland, to ensure interoperability. -- troels --- ## #41635 — david.zuelke@bitextender.com — 2008-11-04T11:46:37+00:00 URL: https://externals.io/message/41624#41635 · In reply to: #41625 Am 03.11.2008 um 16:41 schrieb Marcus Boerger: > 2) Ther are `iterator_apply()` owww that sounds like it really needs docs : --- ## #41636 — Kalle Sommer Nielsen — 2008-11-04T12:21:42+00:00 URL: https://externals.io/message/41624#41636 · In reply to: #41635 2008/11/4 David Zülke : > Am 03.11.2008 um 16:41 schrieb Marcus Boerger: > > > […] > > owww that sounds like it really needs docs :> http://bugs.php.net/bug.php?id=30185 Long time standing bug :) -- Kalle Sommer Nielsen