strategy

<?php
class StrategyContext
{
    private $strategy = NULL;
    //bookList is not instantiated at construct time
    public function __construct($strategy_ind_id)
    {
        switch ($strategy_ind_id) {
            case "C":
                $this->strategy = new StrategyCaps();
                break;
            case "E":
                $this->strategy = new StrategyExclaim();
                break;
            case "S":
                $this->strategy = new StrategyStars();
                break;
        }
    }
    public function showBookTitle($book)
    {
        return $this->strategy->showTitle($book);
    }
}
interface StrategyInterface
{
    public function showTitle($book_in);
}
class StrategyCaps implements StrategyInterface
{
    public function showTitle($book_in)
    {
        $title = $book_in->getTitle();
        $this->titleCount++;
        return strtoupper($title);
    }
}
class StrategyExclaim implements StrategyInterface
{
    public function showTitle($book_in)
    {
        $title = $book_in->getTitle();
        $this->titleCount++;
        return Str_replace(' ', '!', $title);
    }
}
class StrategyStars implements StrategyInterface
{
    public function showTitle($book_in)
    {
        $title = $book_in->getTitle();
        $this->titleCount++;
        return Str_replace(' ', '*', $title);
    }
}
class Book
{
    private $author;
    private $title;
    function __construct($title_in, $author_in)
    {
        $this->author = $author_in;
        $this->title  = $title_in;
    }
    function getAuthor()
    {
        return $this->author;
    }
    function getTitle()
    {
        return $this->title;
    }
    function getAuthorAndTitle()
    {
        return $this->getTitle() . ' by ' . $this->getAuthor();
    }
}
writeln('BEGIN TESTING STRATEGY PATTERN');
writeln('');
$book             = new Book('PHP for Cats', 'Larry Truett');
$strategyContextC = new StrategyContext('C');
$strategyContextE = new StrategyContext('E');
$strategyContextS = new StrategyContext('S');
writeln('test 1 - show name context C');
writeln($strategyContextC->showBookTitle($book));
writeln('');
writeln('test 2 - show name context E');
writeln($strategyContextE->showBookTitle($book));
writeln('');
writeln('test 3 - show name context S');
writeln($strategyContextS->showBookTitle($book));
writeln('');
writeln('END TESTING STRATEGY PATTERN');
function writeln($line_in)
{
    echo $line_in . "<br/>";
}
?>