Expressions: Class Operations
Instantiation
Classes can be instantiated using the new operator, followed by the class name, followed by an optional type parameter ( ::<type> ), followed by a comma-separated list of arguments in parentheses.
$foo = new Foo();
$bar = new Bar(1, 2, 3);
$baz = new Baz::<int>(1, 2, 3, 4);
WARNING
Parentheses are required after the class name, even if there are no arguments.
function example(): void {
$a = new Foo;
}
The code above will result in the following error:
error[P0042]: unexpected token `;`, expected `(`
┌─ examples/class-instantiation-without-paren.ara:2:15
│
2 │ $a = new Foo;
│ ^ unexpected token `;`, expected `(`
WARNING
The class name must be either an identifier, or a variable, and cannot be a dynamic expression.
Examples of valid instantiations:
$foo = new Foo();
$bar = new $foo();
If a dynamic expression is used, the parser will throw an error.
function example(): void {
$a = new (foo())();
}
The code above will result in the following error:
error[P0042]: unexpected token `(`, expected an identifier
┌─ examples/dynamic-instantiation.ara:2:12
│
2 │ $a = new (foo())();
│ ^ unexpected token `(`, expected an identifier
Anonymous class instantiation
Anonymous classes can be instantiated using the new operator, followed by class, followed by a comma-separated list of arguments in parentheses.
$foo = new class() {
// ...
};
WARNING
Parentheses are required after the class keyword, even if there are no arguments.
function example(): void {
$a = new class {
// ...
};
}
The code above will result in the following error:
error[P0042]: unexpected token `{`, expected `(`
┌─ examples/anonymous-class-instantiation-without-paren.ara:2:18
│
2 │ $a = new class {
│ ^ unexpected token `{`, expected `(`
Static Method Calls
Static methods can be called on a class using the :: operator, followed by the method name, followed by an optional type parameter ( ::<type> ), followed by a comma-separated list of arguments in parentheses.
Foo::bar();
Foo::baz::<int>(1, 2, 3);
WARNING
The method name must be an identifier, and cannot be a dynamic expression.
function example(): string {
Foo::{bar()}()
}
The code above will result in the following error:
error[P0042]: unexpected token `{`, expected a variable, an identifier, or `class`
┌─ examples/dynamic-static-method-call.ara:2:8
│
2 │ Foo::{bar()}()
│ ^ unexpected token `{`, expected a variable, an identifier, or `class`
Static Method Closure Creation
A closure can be created from a static method using the :: operator, followed by the method name, followed by an optional type parameter ( ::<type> ), followed by (...).
$bar = Foo::bar(...);
$baz = Foo::baz::<int>(...);
Static Property Access
Static properties can be accessed on a class using the :: operator, followed by the property name.
Foo::$bar;
TIP
The :: operator can also be used to access static properties on an object
$foo = new Foo();
$foo::$bar;
WARNING
The property name must be an identifier, and cannot be a dynamic expression.
function example(): string {
Foo::${bar()}
}
The code above will result in the following error:
error[P0042]: unexpected token `$`, expected a variable, an identifier, or `class`
┌─ examples/dynamic-static-property-access.ara:2:8
│
2 │ Foo::${bar()}
│ ^ unexpected token `$`, expected a variable, an identifier, or `class`
Class Constant Access
Class constants can be accessed on a class using the :: operator, followed by the constant name.
Foo::BAR;
TIP
The :: operator can also be used to access constants on an object
$foo = new Foo();
$foo::BAR;
WARNING
The constant name must be an identifier, and cannot be a dynamic expression.
function example(): string {
Foo::{bar()}
}
The code above will result in the following error:
error[P0042]: unexpected token `{`, expected a variable, an identifier, or `class`
┌─ examples/dynamic-constant-access.ara:2:8
│
2 │ Foo::{bar()}
│ ^ unexpected token `{`, expected a variable, an identifier, or `class`