oop-php: How to Call $obj->some_func () automatically before calling $obj->some_attr

You see this title may first think of is __get magic method, Nest also thought, but--

Because I will need to use Json_encode ($obj) to output to JS access, so here the some_attr can only be public.
Then you can not use __get to do it when calling $obj->some_attr ...

Is there anything more "magic" a bit of a way ...?
I really do not want to get a $obj->to_json () This kind of thing ...

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You see this title may first think of is __get magic method, Nest also thought, but--

Because I will need to use Json_encode ($obj) to output to JS access, so here the some_attr can only be public.
Then you can not use __get to do it when calling $obj->some_attr ...

Is there anything more "magic" a bit of a way ...?
I really do not want to get a $obj->to_json () This kind of thing ...

You mean to specify which members are to be serialized within the class:

1) Let your class to implement the Serializable interface (5.1 support), write a Serialize method to return the data json_encode;

2) or to implement the Jsonserializable interface (5.4+).

 
  $name ();    }    protected function _var_a ()    {        $this->var_a = ' a ';        return $this->var_a;    }} $test   = new Test (), $test->_var_a; $str    = Json_encode ($test); Var_dump ($STR);

This is what the demand. Or did I get the wrong idea?
Direct external operation not on the line, why so complex.

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