<?php
class A {
protected function get() {
return 'A';
}
}
class B1 extends A {}
class B2 extends A {
protected function get() {
return 'A';
}
}
class C extends A {
public function foo(A $a) {
echo $a->get(); // will fail depends on $a implementation
// liskov substitution principle failed
}
}
$a = new A();
$b1 = new B1();
$b2 = new B2();
$c = new C();
$c->foo($b1); // ok
$c->foo($b2); // ok
Warning: PHP Startup: Unable to load dynamic library 'sodium.so' (tried: /usr/lib/php/8.3.5/modules/sodium.so (libsodium.so.23: cannot open shared object file: No such file or directory), /usr/lib/php/8.3.5/modules/sodium.so.so (/usr/lib/php/8.3.5/modules/sodium.so.so: cannot open shared object file: No such file or directory)) in Unknown on line 0
AA
Output for 5.0.0 - 5.0.5, 5.1.1 - 5.1.6
A
Fatal error: Call to protected method B2::get() from context 'C' in /in/NSCKW on line 16
Process exited with code 255.
Output for 5.1.0
Fatal error: fatal flex scanner internal error--end of buffer missed in /in/NSCKW on line 25
Process exited with code 255.
Output for 4.4.2 - 4.4.9
Parse error: syntax error, unexpected T_STRING, expecting T_OLD_FUNCTION or T_FUNCTION or T_VAR or '}' in /in/NSCKW on line 4
Process exited with code 255.
Parse error: parse error, unexpected T_STRING, expecting T_OLD_FUNCTION or T_FUNCTION or T_VAR or '}' in /in/NSCKW on line 4
Process exited with code 255.
Output for 4.3.2 - 4.3.4
Parse error: parse error, expecting `T_OLD_FUNCTION' or `T_FUNCTION' or `T_VAR' or `'}'' in /in/NSCKW on line 4
Process exited with code 255.