Вставить значение из переменной

$pol = "GENDER_FEMALE";
 
$petrovich = new Petrovich(Petrovich::$pol);

$petrovich = new Petrovich(Petrovich::'$pol');
$petrovich = new Petrovich(Petrovich::.'$pol'.);

$pol = "GENDER_FEMALE";
 
$name = "Petrovich::";
 
 
$petrovich = new Petrovich($name.$pol);

$petrovich = new Petrovich('Petrovich:: $pol');

<?php
class Petr
{
    const SOME = 10;
}
 
$name = 'SOME';
 
$obj = new ReflectionClass('Petr');
echo $obj->getConstant($name);

$pol = "GENDER_FEMALE";
$petrovich = new Petrovich('Petrovich::$pol');
 
 
не тоже самое что чистый код, не пойму что не так
$petrovich = new Petrovich(Petrovich::GENDER_FEMALE);

//определяем пол пользователя для описания 1-женский, 2-мужской, 3-неопределен
switch ($sex) {
case 1:
$pol_female = "GENDER_FEMALE";
break;
case 2:
$pol_male = "GENDER_MALE";
break;
case 3:
$pol_no = "GENDER_ANDROGYNOUS";
break;
}
$pol = "$pol_female$pol_male$pol_no";
 
 
echo $pol;
 
 
require_once('padej/Petrovich.php');
 
$petrovich = new Petrovich('Petrovich::$pol');
//$petrovich = new Petrovich(Petrovich::GENDER_MALE);
 
 
 
$firstname = "$name"; //имя
$lastname = "$surname"; //фамилия
 
 
echo $petrovich->firstname($firstname, Petrovich::CASE_GENITIVE).'<br />'; //   имя
echo $petrovich->lastname($lastname, Petrovich::CASE_GENITIVE).'<br />'; //     фамилия

$petrovich = new Petrovich($pol === 'GENDER_MALE' ? Petrovich::GENDER_MALE : Petrovich::GENDER_FEMALE);

switch ($sex) {
case 1:
$pol_female = "GENDER_FEMALE";
break;
case 2:
$pol_male = "GENDER_MALE";
break;
case 3:
$pol_no = "GENDER_ANDROGYNOUS";
break;
}
$pol = "$pol_female$pol_male$pol_no";

switch ($sex) {
case 1:
$pol_female = "GENDER_FEMALE";
break;
case 2:
$pol_male = "GENDER_MALE";
break;
case 3:
$pol_no = "GENDER_ANDROGYNOUS";
break;
}
$pol = "$pol_female$pol_male$pol_no";