Description
In strict PHP, you can only assign variables by reference. Things
that are not variables include function calls and constants.
So we begin the herculean task of removing all unneeded references.
Here are some important details about references:
-
Objects are always passed/copied by reference (in the c++ sense).
We can pass an object without the&and still access/modify
its internal data. -
Arrays are passed/copied by value, but not really because of
copy-on-write, which means that it will only make a copy of
the array if you try to modify it. -
References disable copy-on-write. If you have an array that was
copied by value, and then you take a reference to it, you will
immediately make a copy of it, even if the reference doesn't
modify that array.
Moral of the story
Do not use references in an attempt to improve performance. PHP
does all the right performance things behind the scenes if
you are using the language in the intended way.
References are only intended for when you truly want to pass
something to another function and have that function modify it.
For more details, see
http://schlueters.de/blog/archives/125-Do-not-use-PHP-references.html