No PHP existe algo similar ao Rails com o comando yield ? Algo como :
<html>
<head>
<title>Minha loja</title>
<meta charset="utf-8">
<!-- Latest compiled and minified CSS -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
<link href="css/loja.css" rel="stylesheet" />
</head>
<body>
<div class="container">
<div class="principal">
<?php
yield
?>
</div>
</div>
</body>
</html>