Please have a look at this:

http://www.sspaste.com/paste/show/50fc8a072fc12:

01	<?php
02	 
03	$myDataList = MyDataObject::get();
04	 
05	//option 1
06	$myDataList = $myDataList->Filter("MyField", 1);
07	 
08	 
09	//option 2
10	$myDataList->Filter("MyField", 1);
11	 
12	return $myDataList
13	 
14	// QUESTION: does option 1 return the same as 2?  Is that something that is different between 3.0 and 3.1?

This is a really important question. My answer is that option 1 is not the same as option 2. This surprises me and does not seem intuitive.

I would love to hear some thoughts on this.

Nicolaas

You can think of DataLists as immutable. In 3.0, this wasn't always the case (but is in this one). This means that methods that alter the representation of the list (so things like filter, exclude and sort though not things that alter the data like add and remove) return new instances of the list without changing the current variable.

Simon, thank you very much for the reply. Disappointing it is so unclear (not your answer, the API itself).

Thanks again Simon for your answer, also see: https://github.com/silverstripe/sapphire/pull/1020 for more information.

also see: https://groups.google.com/forum/#!topic/silverstripe-dev/DzwcedAy6AQ