Make ArrayCollection $_elements protected for extensibility

[redthor]

Enhancement request.

Could we get ArrayCollection::$_elements to be visibility protected? toArray() will not pass by reference and so we would have to pull all the elements out and then reload them if we want to do something like a reorder().

It would go well with the new Collection enhancement doctrine/mongodb-odm#1385

( See also related doctrine/mongodb-odm#1458 )

Thanks!

[malarzm]

Just a small clarification, collection enhancement in question is doctrine/mongodb-odm#1219 as support for sharded collection is for Mongo related stuff

[Ocramius]

Please see doctrine/collections#80

[stof]

@redthor I don't see anything in doctrine/mongodb-odm#1385 related to doctrine/collection. It is talking about MongoDB collections