getter setter - PHP magic methods behave differently when dynamically building property names -

i have 2 examples of simple class using __set() , __get() magic methods. 1 throws fatal error , other not when attempting access protected property unset() function.

in example 1, i'm naming protected property starting underscore , allowing access via friendly name , prepending underscore in __set() , __get() methods. (effectively exposing property without underscore).

in example 2, i'm not starting name underscore , allowing access via name directly in __set() , __get() methods.

questions

1) why example 1 not throw fatal error while example 2 does throw fatal error? expect either both throw error or neither throw error.

2) also, why example 1 not unset property? expect property not contain value after unset() function called.

example 1

class example {      protected $_my_property;      function __get($name) {         echo '<h4>__get() triggered!</h4>';         $name = '_' . $name;         if (property_exists($this, $name)) {             return $this->$name;         }         else {             trigger_error("undefined property in __get(): $name");             return null;         }     }      function __set($name, $value) {         echo '<h4>__set() triggered!</h4>';         $name = '_' . $name;         if (property_exists($this, $name)) {             $this->$name = $value;             return;         }         else {             trigger_error("undefined property in __set(): {$name}");         }     }  }  $myexample = new example(); $myexample->my_property = 'my_property has value'; echo $myexample->my_property; unset($myexample->my_property); echo "did unset property?: {$myexample->my_property}"; 

example 2

class example {      protected $my_property;      function __get($name) {         echo '<h4>__get() triggered!</h4>';         if (property_exists($this, $name)) {             return $this->$name;         }         else {             trigger_error("undefined property in __get(): $name");             return null;         }     }      function __set($name, $value) {         echo '<h4>__set() triggered!</h4>';         if (property_exists($this, $name)) {             $this->$name = $value;             return;         }         else {             trigger_error("undefined property in __set(): {$name}");         }     }  }  $myexample = new example(); $myexample->my_property = 'my_property has value'; echo $myexample->my_property; unset($myexample->my_property); echo "did unset property?: {$myexample->my_property}"; 

as side note, simplistic example demonstrates behavior i'm seeing in real world project. thanks!

the problem have have not defined __unset() magic method.

this means when call unset($myexample->my_property), trying directly unset public property specified name.

in example 1, real protected property has underscore in it's name. therefore, when try unset property, php looks @ object, sees there nothing specified name, , ignores it.

this same behaviour unset() exhibit if tried unset non-existent variable or array element.

however in example 2, protected property has same name have given in unset() call.

in example, php looks @ object , sees property exist it non-accessible. therefore throws error complaining can't unset property.

you can resolve issue including __unset() method alongside __get() , __set() methods. if you're planning use magic methods, should ideally define three.

hope helps.