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<?xml version="1.0"?>
<document>
<properties>
<author email="jbjk@mac.com">John Keyes</author>
<title>Introduction</title>
</properties>
<body>
<section name="Introduction">
<p>
There are three stages to command line processing. They are the
definition, parsing and interrogation stages. The following
sections will discuss each of these stages in turn, and discuss how
to implement them with CLI.
</p>
</section>
<section name="Definition Stage">
<p>
Each command line must define the set of options that will be used
to define the interface to the application.
</p>
<p>
CLI uses the <a href="apidocs/org/apache/commons/cli/Options.html">
Options</a> class, as a container for
<a href="apidocs/org/apache/commons/cli/Options.html">
Option</a> instances. There are two ways to create
<code>Option</code>s in CLI. One of them is via the constuctors,
the other way is via the factory methods defined in
<code>Options</code>.
</p>
<p>
The <a href="usage.html">Usage Scenarios</a> document provides
examples how to create an <code>Options</code> object and also
provides some real world examples.
</p>
<p>
The result of the definition stage is an <code>Options</code>
instance.
</p>
</section>
<section name="Parsing Stage">
<p>
The parsing stage is where the text passed into the
application via the command line is processed. The text is
processed according to the rules defined by the parser
implementation.
</p>
<p>
The <code>parse</code> method defined on
<a href="apidocs/org/apache/commons/cli/CommandLineParser.html">
CommandLineParser</a> takes an <code>Options</code>
instance and a <code>java.util.List</code> of arguments and
returns a
<a href="apidocs/org/apache/commons/cli/CommandLine.html">
CommandLine</a>.
</p>
<p>
The result of the parsing stage is a <code>CommandLine</code>
instance.
</p>
</section>
<section name="Interrogation Stage">
<p>
The interrogation stage is where the application querys the
<code>CommandLine</code> to decide what execution branch to
take depending on boolean options and to use the option values
to provide the application data.
</p>
<p>
This stage is implemented in the user code. The accessor methods
on <code>CommandLine</code> provide the interrogation capability
to the user code.
</p>
<p>
The <a href="usage.html">Usage Scenarios</a> document provides examples
how to create an <code>Options</code> object.
</p>
<p>
The result of the interrogation stage is that the user code
is fully informed of all the text that was supplied on the command
line and processed according to the parser and <code>Options</code>
rules.
</p>
</section>
</body>
</document>
|
