Change bp_sort_by_key() to allow key preservation.

[dcavins]

bp_sort_by_key() internally uses usort() which discards keys once the sort is completed. I'd like to make it possible to keep the keys when helpful.

In the attached patch, I've added a new parameter to bp_sort_by_key() that runs the results through uasort() instead of usort().

[dcavins]

Add $preserve_keys parameter to bp_sort_by_key().

[dcavins]

There's a related convenience function bp_alpha_sort_by_key() that I did not update to keep keys. It would be simple to do, but do we want to?

​https://buddypress.trac.wordpress.org/browser/trunk/src/bp-core/bp-core-functions.php#L104

[r-a-y]

Patch looks nice and simple to me! +1!

[DJPaul]

what problems would just changing the current implementation cause, rather than adding a new parameter?

[dcavins]

I'm not sure it would cause any (I just searched the repo for uses, which are not too numerous), but I'm not going to make that call. :)

It doesn't appear to throw a notice if applied to a non-associative array, so at least it's not a no-go.

[dcavins]

Well, this is interesting. Simply changing usort() out for uasort() seems to work OK for our uses of bp_sort_by_key(), but we've got a test that sorts an object that breaks:
​https://buddypress.trac.wordpress.org/browser/trunk/tests/phpunit/testcases/core/functions.php#L295

Other tests of non-assocative arrays that also fail can be fixed like this (assertEquals compares keys, values and order):
$this->assertEquals( $expected, array_values( bp_sort_by_key( $items, 'value', 'num' ) ) );

Is that test sorting an object a good case for keeping usort(), or is it testing an unlikely use of bp_sort_by_key()?

Opinions welcome! :)

[boonebgorges]

The fact that a tests is failing suggests to me that we should take the conservative route, and add the preserve_keys parameter. This is a semi-standard convention in PHP's array functions, so I think it's transparent enough.

[dcavins]

In 11082:

bp_sort_by_key(): Add $preserve_keys parameter.

Add a parameter to bp_sort_by_key() so that it calls either usort()
or uasort(), depending on the whether the array keys are important or
not.

Fixes #7238.