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<title>BeanShell Dynamic Typing</title><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="index.html" title="jEdit 5.6 User's Guide"><link rel="up" href="macro-basics.html" title="Chapter 13. Macro Basics"><link rel="prev" href="helpful-methods.html" title="Helpful Methods in the Macros Class"><link rel="next" href="something-useful.html" title="Now For Something Useful"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">BeanShell Dynamic Typing</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="helpful-methods.html">Prev</a> </td><th width="60%" align="center">Chapter 13. Macro Basics</th><td width="20%" align="right"> <a accesskey="n" href="something-useful.html">Next</a></td></tr></table><hr></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="dynamic-typing"></a>BeanShell Dynamic Typing</h2></div></div></div><p>Without an explicit <em class="glossterm">type declaration</em> like
<code class="classname">String</code> <code class="varname">result</code>, BeanShell
variables can change their type at runtime depending on the object or
data assigned to it. This dynamic typing allows you to write code like
this (if you really wanted to):</p><div class="informalexample"><pre class="programlisting">// note: no type declaration
result = Macros.input(view, <span class="quote">“<span class="quote">Type something here.</span>”</span>);
// this is our predefined, current View
result = view;
// this is an <span class="quote">“<span class="quote">int</span>”</span> (for integer);
// in Java and BeanShell, int is one of a small number
// of <span class="quote">“<span class="quote">primitive</span>”</span> data types which are not classes
result = 14;</pre></div><p>However, if you first declared <code class="varname">result</code> to be
type <code class="classname">String</code> and and then tried these
reassignments, BeanShell would complain. While avoiding explicit type
declaration makes writing macro code simpler, using them can act as a
check to make sure you are not using the wrong variable type of object
at a later point in your script. It also makes it easier (if you are so
inclined) to take a BeanShell <span class="quote">“<span class="quote">prototype</span>”</span> and incorporate
it in a Java program.</p><p>One last thing before we bury our first macro. The double slashes
in the examples just above signify that everything following them on
that line should be ignored by BeanShell as a comment. As in Java and
C/C++, you can also embed comments in your BeanShell code by setting
them off with pairs of <strong class="userinput"><code>/* */</code></strong>, as in the following
example:</p><div class="informalexample"><pre class="programlisting">/* This is a long comment that covers several lines
and will be totally ignored by BeanShell regardless of how
many lines it covers */</pre></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="helpful-methods.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="macro-basics.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="something-useful.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Helpful Methods in the Macros Class </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Now For Something Useful</td></tr></table></div></body></html>
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