title: Force child classes to override a particular function in PHP
body: <p>I am creating a reporting library in PHP and developed an abstract class named <strong>ReportView</strong>. This will provide the basic functionality of a report like Generating header and footer, create parameter form. </p>
  
  <p>There will be another function named <strong>generate_report</strong> in this class. Currently it is empty in abstract class as at this level we do not know the contents of report. Further it includes a <strong>render</strong> function which calls this generate_report function and sends output to browser.</p>
  
  <blockquote>
    <p>So I need whenever a child class inherits from ReportView it must implement
    the generate_report method otherwise PHP must give error. Is there any keyword or method through which we can enforce implemetation of a specific function.</p>
  </blockquote>