Upgrading to PHP 7

Chapter 10. Changes in Object-Oriented Programming

Considering that PHP 5.0 and almost every subsequent release were primarily about changes to the object model, it might seem odd that there are hardly any changes to it in PHP 7.0.

But, few though they may be, PHP 7.0 still brings some new powerful OOP features to the table.

Context-Sensitive Lexer

PHP 7.0 introduces the context-sensitive lexer, which allows for the use of keywords as names for properties, methods, and constants within classes, interfaces, and traits.

What this means is that PHP goes from having 64 reserved keywords to having just one—class—and only in the class constant context.

You may now use any of the following keywords as property, function, and constant names:

callable	and	include	function
trait	global	include_once	if
extends	goto	throw	endswitch
implements	instanceof	array	finally
static	insteadof	print	for
abstract	interface	echo	foreach
final	namespace	require	declare
public	new	require_once	case
protected	or	return	do
private	xor	else	while
const	try	elseif	as
enddeclare	use	default	catch
endfor	var	break	die
endforeach	exit	continue	self
endif	list	switch	parent
endwhile	clone	yield	class

The only exception is that you still cannot use const class, because it clashes with the fully qualified class name magic constant added in PHP 5.5.

PHP 4 Constructors Deprecated

While some called for them to be removed, the old PHP 4 constructors have instead been marked as ...