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NOCpulse::CommandLineApplicationComponent.3pm

NAME

NOCpulse::CommandLineApplicationComponent - an abstract superclass for classes that participate in the use of command line switches in an application.

SYNOPSIS

         package MyClass;
         use NOCpulse::CommandLineApplicationComponent;
         @ISA qw(NOCpulse::CommandLineApplicationComponent);
         
         sub overview {
             my $self = shift();
             return "This component provides access to a shell via ssh";
         }
         
         sub registerSwitches {
             my $self = shift();
             $self->SUPER::registerSwitches; # good practice
             $self->addSwitch('login','=s',1,'root@localhost','SSH login string');
             $self->addSwitch('command','=s',1,'/bin/true','Command to run');
         }
         
         sub doit {
             my $self = shift();
             my $login = $self->get_login;
             my $command = $self->get_command;
             return `ssh $login $command`
         }
         
         package main;
         
         use MyClass;        
         $thing = MyClass->newInitialized;
         if ($thing->commandLineIsValid) {
          print $thing->doit;
         } else {
          $thing->printUsage;
         }
 
 

DESCRIPTION

NOCpulse::CommandLineApplicationComponent helps you write modular command line applications without having to worry about dealing with command line switch specifications and validation, and without having to deal with writing help methods.

The typical NOCpulse::CommandLineApplicationComponent based application will have one or more subclasses of this class, with one of them acting as a ``driver'' for the rest (e.g. it would be responsible for dealing with a --help switch).

It is especially handy for doing ``polymorphic command line apps'', where documentation and switch requirements change depending on other switches (e.g. you can have a switch in the mainline that specifies one or more classes that must be used/instantiated dynamically).

REQUIRES

NOCpulse::PersistentObject, NOCpulse::CommandLineSwitch, Text::Wrap, Carp

MODULE VARIABLES

@Instances - holds all instances of if this class and its subclasses

CLASS VARIABLES

$OutputTarget

==cut

CLASS METHODS

AddInstance()

Register an instance with the NOCpulse::CommandLineApplicationComponent class. This is done automatically as part of object construction - you should probably never call this.

commandLineIsValid()

(can also be called as an instance method) Called by the mainline logic in your application only once, this causes all switches in all components to calculate their validity. If everything is valid, this returns true, else false.

printUsage()

(can be called as an instance method) Prints usage for all NOCpulse::CommandLineApplicationComponent instances in the current application.

printUsageNotes()

Callout for subclasses to add extra info to its usage - by default does nothing.

printUsageAsXML()

(can be called as an instance method) Prints usage for any components that have problems with any command line switch.

INSTANCE METHODS

registerSwitches()

Abstract method - you must override this in your subclass and make calls to addSwitch() if your component needs switches. This method gets called automatically during initialization of the component.

overview()

Abstract method - you must override this and define it such that it returns a string describing the component.

newNamed(<name>)

Overrides NOCpulse::PersistentObject behavior, which would cache the instance Cpulse:: in a way that is not useful to us here ( NOCpulse::PersistentObject uses a hash, we want an array)

instVarDefinitions()

Defines the following variables:

    usage - (I don't think this is used - it's probably cruft)
 
    switches - A hash of all the switches this component defines/owns ( name=>value where
    value is an instance of NOCpulse::CommandLineSwitch)
 
 

initialize()

Initializes all switches. If you override this in your subclass(es), be SURE to call $self->SUPER::initialize !!

switchesAreValid()

Returns true if switches are valid for this component

switchValue(<name>)

Returns the value of the switch whose name is <name>. You can get here via get_name as well (see doesNotUnderstand).

hasSwitch(<name>)

Returns true if a switch whose name is <name> exists.

switch(<name>)

Returns the switch object whose name is <name>.

switchIsValid(<name>)

Returns true if a switch whose name is <name> is valid.

addSwitch(<name>,<spec>,<required>,<default>,<usage>)

Adds a NOCpulse::CommandLineSwitch object as described by the parameters to this method to the component.

<name> = the name of the switch <spec> = the Getopt::Long specification for the switch <required> = if true, the switch is required <default> = default value for the switch (use undef if none exists) <usage> = a string describing the switch

hasSwitches()

Returns a (possibly empty) list of the names of all switches defined for the component.

print()

Printing via this method allows you to redirect output to $NOCpulse::CommandLineApplicationComponent::OutputTarget, which may be a glob or object or scalar.

usageAsSql()

Returns a string consisting of sql commands that update NOCpulse tables which describe probes and their switches.

doesNotUnderstand()

Adds to NOCpulse::PersistentObject doesNotUnderstand logic such that calls to get_xxx will also return the value of a switch whose name is xxx

FreeAllInstances()

Cause all instances of NOCpulse::CommandLineApplicationComponent to be cleared from memory (assuming nothing else is holding on to them).

POD ERRORS

Hey! The above document had some coding errors, which are explained below:

Around line 371:

You forgot a '=back' before '=head1'

Around line 379:

You forgot a '=back' before '=head1'

Around line 422:

You forgot a '=back' before '=head1'