Spotting References
Many syntax constructs in PHP are implemented via referencing
mechanisms, so everything told above about reference binding also
apply to these constructs. Some constructs, like passing and
returning by-reference, are mentioned above. Other constructs that
use references are:
global References
When you declare variable as global $var you
are in fact creating reference to a global variable. That means,
this is the same as:
That means, for example, that unsetting $var
won't unset global variable.
$this
In an object method, $this is always reference
to the caller object.
