Question

I can’t seem to get any consistent info on this. Different sources appear to say different things and the venerable php.net itself (appears) not to explicitly state this – although, I must admit, I only had a quick look.

In cases where I am passing around ‘heavy’ objects, I need to pass by reference, but I don’t want to keep typing:

function foo(TypeName& $obj)

if I can get away with simply

function foo(TypeName $obj)

So what does the standard say?

Answer 1

Objects are passed (and assigned) by reference. No need to use address of operator.

Granted what I typed is an oversimplification but will suit your purposes. The documentation states:

One of the key-points of PHP5 OOP that
is often mentioned is that “objects
are passed by references by default”.
This is not completely true. This
section rectifies that general thought
using some examples.

A PHP reference is an alias, which
allows two different variables to
write to the same value. As of PHP5,
an object variable doesn’t contain the
object itself as value anymore. It
only contains an object identifier
which allows object accessors to find
the actual object. When an object is
sent by argument, returned or assigned
to another variable, the different
variables are not aliases: they hold a
copy of the identifier, which points
to the same object.

For a more detailed explanation (explains the oversimplification as well as identifiers) check out this answer.