Call to a member function X on a non-object in Y on line Z

Question

<?php
class Conversor {
 function toLowerFirst($word) {
  $word = 'test';
  return $word;
 }
}

class Test {
 function test() {
  $word = 'Test';
  $word = $this->conversor->toLowerFirst($word);
  echo $word;
 }
}

class Launcher {
 function launch() {
  $Test = new Test();
  $Test->conversor = new Conversor();
  $Test->test();
 }
}

$launcher = new Launcher();
$launcher->launch();
?>

Why doesn't it echo 'test'?

Answer 1

It's because your function test() is the same as the class name - it looks like an old-style constructor, so it's being run when you do new Test(), i.e. before you set conversor.

Rename the function or add a new-style constructor to Test: __construct()

Answer 2

Because the call $word = $this->conversor->toLowerFirst($word); returns an error, the function toLowerFirst doesn't exist at that time (you call the function through a non-existant instance of Conversor)

Replace $word = $this->conversor->toLowerFirst($word); with $word = Conversor::toLowerFirst($word); and it will work.

Edit: the __construct is a better solution, because my suggestion results in 2 times the echo.. (test is treated as a constructor for Test)