Section 5.1 Programs

<section xml:id="inactive-code">
  <title>Programs</title>

  <p>
    First, some samples of programs that are not interactive. They will be
    syntax highlighted if a valid <attr>language</attr> is specified.
    Optionally, lines can be numbered and selected lines highlighted.
  </p>
  <!-- This example also appears in the PreTeXt Guide (doc/guide/author/topics.xml).  Apply any edit to both copies. -->
  <listing>
    <title>A static Java program with highlighted lines</title>

    <program language="java" line-numbers="yes" highlight-lines="2,6-8">
      <code>
              import javax.swing.JFrame;  //Importing class JFrame
              import javax.swing.JLabel;  //Importing class JLabel
              public class HelloWorld {
                  public static void main(String[] args) {
                      JFrame frame = new JFrame();           //Creating frame
                      frame.setTitle("Hi!");                 //Setting title frame
                      frame.add(new JLabel("Hello, world!"));//Adding text to frame
                      frame.pack();                          //Setting size to smallest
                      frame.setLocationRelativeTo(null);     //Centering frame
                      frame.setVisible(true);                //Showing frame
                  }
              }
      </code>
    </program>
  </listing>

  <p>
    Instead of specifying <attr>language</attr> on each program, a default can
    be specified at <c>docinfo/programs/@language</c>. That value will be used
    for any program that lacks a <attr>language</attr> attribute. This sample
    does not specify it's own <attr>language</attr> and is relying on the
    default set in this book.
  </p>

  <listing>
    <title>Python program, relying on default programs language</title>

    <program line-numbers="yes">
      <code>
              def say_hello():
                  print("Hello, World!")

              say_hello()
      </code>
    </program>
  </listing>
</section>