Ask PHP from which version to start supporting the new $variable () instantiation class

Which version does PHP start with to support the new $variable () instantiation class?
Title, use a variable to specify a class name, through the new instance object, which version of PHP is supported from?
The PHP manual was not found, and even this was not seen.

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It's early, isn't it? PhP4 There are instances of the class AH. $a =new B (); or $a =new B;
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Classes and Objects (PHP 4) Inherit classes and Objects (PHP 4)
PHP Manual

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Class
A class is a collection of variables and functions that act on those variables. variables are defined by VAR, functions are defined by function, and classes are defined by the following syntax

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PhP4
With the introduction of classes, that's how it's written.
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4, I brought it.

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