Terminology question on “dereferencing”?

Question

In PHP, the following code is valid

$a=array(0);$a[0];

but that one is invalid:

array(0)[0]

1. What is the terminology corresponding to that behaviour? (has it anything to do with "dereferencing"?)
2. What is the motivation behind such a behaviour (besides user spite :-P)

I am looking for the general terminology, not necessarily the terminology associated with PHP.

(Other example: in MATLAB, the following is valid:

s = size(M)
s(0)

but that is invalid:

size(M)(0)

In both PHP and MATLAB, adding parenthesis does not help, i.e., (array(0))[0] and (size(M))(0) are both invalid)

Answer 1

That's called Array dereferencing, and will become available in PHP 5.4 (which is currently in alpha)

Note (thanks Gordon) : what you are asking for, with array()¹, is not possible even in PHP 5.4 -- but it'll work for functions.

A couple of sources :

• RFC - Function Array Dereferencing
• Features in PHP trunk: Array dereferencing, when it was unsure whether there would be a PHP 5.4 or a PHP 6
• And, last but not least, the (currently last) news on php.net : PHP 5.4 alpha1 released

Quoting that last news :

Here is an incomplete list of changes:
- Added: Traits language construct
- Added: Array dereferencing support
- Added: DTrace support
- Improved: Improved Zend Engine memory usage and performance
- Moved: ext/sqlite moved to pecl (sqlite3 support is still built-in)

^1._{array() is not a function, even if it looks like one -- it's actually what PHP calls a language construct ; and those don't behave like functions.}

Answer 2

This is called "array dereferencing" and it will be available for use in PHP5.4.