PHP 8.2 introduces read-only classes
A major update to the stalwart scripting language for web development, PHP 8.2 has arrived with performance, syntax, and type safety improvements along with new capabilities such as read-only classes and stand-alone types.
PHP 8.2 was published December 8 and can be accessed from php.net.
Support for read-only classes in PHP 8.2 means that a class marked with the readonly
modifier will mark all instance properties of the class as read-only and prevent the creation of dynamic properties. Marking readonly
classes with the AllowDynamicProperties
attribute triggers a compile error.
The addition of null
, false
, and true
as stand-alone types in PHP 8.2 is described as a “programming enhancement.” The null type corresponds to PHP’s unit type (the type that holds a single value) while false
and true
are literal types of type bool
. These changes promote type system completeness and serve a number of edge cases.
In other improvements in PHP 8.2:
- Disjunctive normal form (DNF) types enable the combination of union and intersection types, following a strict rule that says when combining union and intersection types, intersection types must be grouped with brackets.
- A “random” extension provides an object-oriented API to random number generation.
- The creation of dynamic properties has been deprecated, to help avoid mistakes and typos, unless the class opts in by using the
AllowDynamicProperties
attribute;stdclass
allows dynamic properties. - New classes, interfaces, and functions are featured, such as a
msqli_execute_query
function and aSensitiveParameter
attribute. - Constants now can be defined in traits.
- The
$
string interpolation has been deprecated.
PHP 8.1, which featured new capabilities regarding enums, syntax, and read-only properties, arrived in November 2021. It was followed by several point releases.
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