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--- rfc:pass_scope_to_magic_accessors [2023/01/19 16:56] – nicolasgrekas
+++ rfc:pass_scope_to_magic_accessors [2023/01/19 17:39] – nicolasgrekas
@@ Line 14: / Line 14: @@
 This RFC proposes to pass their calling scope to magic accessors: ''%%__get()%%'', ''%%__set()%%'', ''%%__isset()%%'', ''%%__unset()%%'', ''%%__call()%%'' and ''%%__callStatic()%%''.
-The calling scope defined as the name of the class that is calling a magic method. It's a string. It can also be null when a magic method is called outside of any class context, as is the case when calling them from the global scope or from the body of a named function. For closures, their scope is the class name they were created in (if any), or their rebound scope when using ''Closure::bind()''. The calling scope is also the piece of information that is found under key ''"class"'' of frames returned by ''debug_backtrace()''.
+The calling scope is defined as the name of the class that is calling a magic method. It's a string. It can also be null when a magic method is called outside of any class context, as is the case when calling them from the global scope or from the body of a named function. For closures, their scope is the class name they were created in (if any), or their rebound scope when using ''Closure::bind()''. The calling scope is also the piece of information that is found under key ''"class"'' of frames returned by ''debug_backtrace()''.
+Here are some examples:
+<PHP>
+class Foo {
+    private $abc;
+    public function __construct()
+    {
+        unset($this->abc); // enables magic methods when accessing the property
+    }
+    public function __get($name) {
+        var_dump(debug_backtrace()[1]['class'] ?? null);
+    }
+}
+$foo = new Foo();
+$foo->abc; // NULL
+class Bar {
+    public function __construct($foo) {
+        $foo->abc;
+    }
+}
+$bar = new Bar($foo); // string(3) "Bar"
+$f = fn ($foo) => $foo->abc;
+$f($foo); // NULL
+$g = \Closure::bind($f, null, Bar::class);
+$g($foo); // string(3) "Bar"
+</PHP>
 Passing the calling scope to magic accessors would help to properly implement visibility-related logic. Right now, we have to call ''debug_backtrace()'' to write scope-sensitive logic, but it's very difficult to get it right: accounting for inheritance is hard (calling e.g. ''%%parent::__get()%%'' changes the outcome of ''debug_backtrace()'' inside this ''%%parent::__get()%%'' method.) Passing the calling scope would make this concern more evident and would solve the issue with inheritance. It would also fix the edge case of calling a magic method via ''ReflectionProperty::get/setValue()'', where looking up at ''debug_backtrace()'' needs special care to extract the calling scope. Last but not least, removing calls to ''debug_backtrace()'' would improve the performance of such magic accessors.

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