foo-and-bar.php

<?php

class Foo {
  public function doSomething() {
     // ... 60 lines of code here....
  }
}

class Bar {
  protected $foo;

  public function __construct(Foo $foo) {
     $this->foo = $foo;
  }

  public function doBarStuf() {
    // ...
  }

  public function doOtherBarStuff() {
    // ...
  }

  public function doSomethingRelatedFoo() {
    $retval = $this->foo->doSomething();
    // ...
  }

}