Clad User Manual: Difference between revisions

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The framework scans the command line looking for the first argument that can be mapped to a command.  
The framework scans the command line looking for the first argument that can be mapped to a command.  


The mapping process involves scanning the classpath and looking for classes implementing the [https://github.com/NovaOrdis/clad/blob/master/src/main/java/io/novaordis/clad/command/Command.java Command interface]. The current version does not introspect all classes, but just those whose simple class name match the following pattern: <tt><commandName>Command</tt>.  
The mapping process involves scanning the classpath and looking for classes implementing the [https://github.com/NovaOrdis/clad/blob/master/src/main/java/io/novaordis/clad/command/Command.java Command interface]. The current version does not introspect all classes, but just those whose simple class name match the following pattern: <tt><commandName>Command</tt>. All arguments between the wrapper name and the command name are interpreted as global options. All arguments following the command name are interpreted as command options.
 
All arguments between the wrapper name and the command name are interpreted as global options.
 
All arguments following the command name are interpreted as command options.
 
<pre>
 
  wrapper [global-options] command [command-options]
 
</pre>
 
=Options=
 
The options use the GNU command line convention:
 
<pre>
 
-o <value> | --option=<value>
 
</pre>
 
=Configuration File=
 
Each command line option has a configuration file correspondent. Command line value takes precedence over the configuration file value.
 
=Implementing a Command Line Application=
 
<font color=red>
 
Implement <tt>[https://github.com/NovaOrdis/clad/blob/master/src/main/java/io/novaordis/clad/application/ApplicationRuntime.java ApplicationRuntime]</tt> interface or extend <tt>[https://github.com/NovaOrdis/clad/blob/master/src/main/java/io/novaordis/clad/application/ApplicationRuntimeBase.java ApplicationRuntimeBase]</tt>
 
Package the application runtime implementation class and the commands in a JAR (or place them in a directory).
 
Set “<tt>application.name</tt>” as a system property. If the application runtime implementation class is <tt>BlueApplicationRuntime</tt>, the application.name must be “blue”.
 
Make sure the JAR or the directory is first on the class path (otherwise other <tt><your-command-name>Command.class</tt>, if exist, will be instantiated first).
 
</font>
 
==In-line Application Help==
 
If a text file named <tt><application-name>.txt</tt> is placed in the same package as the <tt>ApplicationRuntime</tt> implementation class, its content is rendered to <tt>stdout</tt> every time the in-line application help is invoked with no-argument "help" command:
 
<pre>
  <app-name> help|--help|-h
</pre>
 
===Macros===
 
The help renderer recognizes several macros, which are replaced by dynamically generated content at runtime.
 
@COMMANDS@ - inserts the list of commands available to the application. The runtime builds that list via introspection looking for classes that implement the Command interface.
 
=Implementing a Command=
 
Implement the [https://github.com/NovaOrdis/clad/blob/master/src/main/java/io/novaordis/clad/command/Command.java Command] interface.
 
The implementation class must be named <tt><command-name>Command</tt>.
 
Example: <tt>PrintCommand</tt> will be matched to the "<tt>print</tt>" command. <tt>BusinessScenarioCommand</tt> will be matched to the "<tt>business-scenario</tt>" command.
 
==Relationship between Command and ApplicationRuntime==
 
If a specific command does not need an application runtime instance (thus the framework is not required to instantiate an application runtime for it), the <tt>Command.needsRuntime()</tt> implementation must return <tt>false</tt>. By default <tt>CommandBase.needsRuntime()</tt> returns <tt>true</tt>.
 
==In-Line Command Help==
 
If a text file named <tt><command-name>.txt</tt> is placed in the same package as the command implementation class, the framework will send the content of the file to <tt>stdout</tt> when in-line command help is requested:


<pre>
<pre>
    <wrapper> help|--help|-h <command>
wrapper [global-options] command [command-options]
</pre>
</pre>


==Command Execution==
=Subjects=


<tt>execute()</tt> will be called on the main thread.
<blockquote style="background-color: #f9f9f9; border: solid thin lightgrey;">
:[[clad User Manual - Concepts|Concepts]]
:[[clad User Manual - How to Implement a Command Line Application|How to Implement a Command Line Application]]
</blockquote>

Latest revision as of 18:17, 8 November 2016

Internal

Overview

The framework scans the command line looking for the first argument that can be mapped to a command.

The mapping process involves scanning the classpath and looking for classes implementing the Command interface. The current version does not introspect all classes, but just those whose simple class name match the following pattern: <commandName>Command. All arguments between the wrapper name and the command name are interpreted as global options. All arguments following the command name are interpreted as command options. 

wrapper [global-options] command [command-options]

Subjects

Concepts
How to Implement a Command Line Application
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