Example of trait with private

TestTrait.php

<?php

trait TestTrait
{
  private $foo;

  protected function upFoo()
  {
    $this->foo++;

    return $this->foo;
  }
}

class TestClass
{
  use TestTrait;

  public function example()
  {
    $bar = $this->upFoo();

    print "bar is $bar\n";
  }
}

class TestExtended extends TestClass
{
  public function otherExample()
  {
    $baz = $this->upFoo();

    print "baz is $baz\n";
  }

}

$test = new TestClass();

$test->example();

$test2 = new TestExtended();

$test2->example();
$test2->otherExample();