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a50198d0fe
RFC: https://wiki.php.net/rfc/null_coalesce_equal_operator $a ??= $b is $a ?? ($a = $b), with the difference that $a is only evaluated once, to the degree that this is possible. In particular in $a[foo()] ?? $b function foo() is only ever called once. However, the variable access themselves will be reevaluated.
128 lines
1.7 KiB
PHP
128 lines
1.7 KiB
PHP
--TEST--
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Coalesce assign (??=): Basic behavior
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--FILE--
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<?php
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// Refcounted values
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$foo = "fo";
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$foo .= "o";
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$bar = "ba";
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$bar .= "r";
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// Identity function used to track single-evaluation
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function id($arg) {
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echo "id($arg)\n";
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return $arg;
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}
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echo "Simple variables:\n";
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$a = 123;
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$a ??= 456;
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var_dump($a);
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$b = null;
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$b ??= $foo;
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var_dump($b);
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$c = $foo;
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$c ??= $bar;
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var_dump($c);
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$d ??= $foo;
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var_dump($c);
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echo "\nArrays:\n";
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$ary = [];
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$ary["foo"] ??= 123;
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$ary[$foo] ??= $bar;
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$ary[$bar] ??= $foo;
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var_dump($ary);
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$ary = [];
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$ary[id($foo)] ??= 123;
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$ary[id($foo)] ??= $bar;
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$ary[id($bar)] ??= $foo;
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var_dump($ary);
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echo "\nObjects:\n";
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$obj = new stdClass;
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$obj->foo ??= 123;
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$obj->$foo ??= $bar;
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$obj->$bar ??= $foo;
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var_dump($obj);
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$obj = new stdClass;
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$obj->{id($foo)} ??= 123;
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$obj->{id($foo)} ??= $bar;
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$obj->{id($bar)} ??= $foo;
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var_dump($obj);
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class Test {
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public static $foo;
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public static $bar;
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}
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echo "\nStatic props:\n";
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Test::$foo ??= 123;
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Test::$$foo ??= $bar;
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Test::$$bar ??= $foo;
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var_dump(Test::$foo, Test::$bar);
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Test::$foo = null;
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Test::$bar = null;
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Test::${id($foo)} ??= 123;
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Test::${id($foo)} ??= $bar;
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Test::${id($bar)} ??= $foo;
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var_dump(Test::$foo, Test::$bar);
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?>
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--EXPECT--
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Simple variables:
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int(123)
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string(3) "foo"
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string(3) "foo"
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string(3) "foo"
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Arrays:
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array(2) {
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["foo"]=>
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int(123)
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["bar"]=>
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string(3) "foo"
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}
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id(foo)
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id(foo)
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id(bar)
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array(2) {
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["foo"]=>
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int(123)
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["bar"]=>
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string(3) "foo"
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}
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Objects:
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object(stdClass)#1 (2) {
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["foo"]=>
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int(123)
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["bar"]=>
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string(3) "foo"
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}
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id(foo)
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id(foo)
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id(bar)
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object(stdClass)#2 (2) {
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["foo"]=>
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int(123)
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["bar"]=>
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string(3) "foo"
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}
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Static props:
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int(123)
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string(3) "foo"
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id(foo)
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id(foo)
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id(bar)
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int(123)
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string(3) "foo"
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