14.7. Interapplication Consistency
Factor out common command-line interface components into a shared module .
Tools such as Getopt::Long, Getopt::Clade, and Getopt::Euclid make it easy to follow the advice of the "Command-Line Structure" guideline to enforce a single consistent command-line structure across all of your applications.If you're using Getopt::Long or Getopt::Clade, you can simply create a module that provides a suitable description of the standard interface. For example, if you're using Getopt::Clade, you might create a module (such as in Example 14-6) that provides the standard interface features that every application is expected to provide:
Example 14-6. Standard interface components for Getopt::Clade
package Corporate::Std::Cmdline;
use strict;
use warnings;
use Getopt::Clade q{
-i[n] [=] <file:in> Specify input file [default: '-']
-o[ut] [=] <file:out> Specify output file [default: '-']
-v Print all warnings
--verbose [ditto]
};
1; # Magic true value required at the end of every module
You could then reuse it in each program you created. For example, you could refactor Example 14-4 to Example 14-7.
Example 14-7. Standardized command-line parsing via Getopt::Clade
# Specify and parse valid command-line arguments...
use Corporate::Std::Cmdline plus => q{
-l[en] [=] <l:+int> Display length [default: 24 ]
-w[id] [=] <w:+int> Display width [default: 78 ]
};
# Report intended behaviour...
if ($ARGV{-v}) {
print "Loading first $ARGV{'-l'} chunks of file: $ARGV{'-i'}\n"
}
# etc.
Getopt::Euclid allows you to construct interface specification modules in a similar way. The main difference is that those modules mainly contain POD (see Example 14-8).
Example 14-8. Standard interface components for Getopt::Euclid
package Corporate::Std::Cmdline;
use Getopt::Euclid;
1; # POD-only modules still need a magic true value at the end
=head1 STANDARD OPTIONS
=over
=item -i[nfile] [=] <file>
Specify input file
=for Euclid:
file.type: readable
file.default: '-'
=item -o[utfile] [=] <file>
Specify output file
=for Euclid:
file.type: writable
file.default: '-'
=item -v[erbose]
Print all warnings
=item --version
=item --usage
=item --help
=item --man
Print the usual program information
=back
Once that module was installed in the normal way, you could refactor Example 14-5 to the implementation shown in Example 14-9. Note that, once again, only the application-specific arguments need to be specified within the application itself.
Example 14-9. Standardized command-line parsing via Getopt::Euclid
# Handle command lines of the form:
#
# > orchestrate -in source.txt -o=dest.orc -verbose
# Create a command-line parser that implements the documentation below...
use Corporate::Std::Cmdline;
# Report intended behaviour...
if ($ARGV{-v}) {
print "Loading first $ARGV{-l} chunks of file: $ARGV{-i}\n"
}
# etc.
_ _END_ _
=head1 NAME
orchestrate - Convert a file to Melkor's .orc format
=head1 VERSION
This documentation refers to orchestrate version 1.9.4
=head1 USAGE
orchestrate -in source.txt -out dest.orc -verbose -len=24
=head1 OPTIONS
=over
=item -l[en] [=] <l>
Display length (default is 24 lines)
=for Euclid:
l.type: integer > 0
l.default: 24
=item -w[id] [=] <w>
Display width (default is 78 columns)
=for Euclid:
w.type: integer > 0
w.default: 78
=back
=head1 STANDARD INTERFACE
See L<Corporate::Std::Cmdline> for a description of the standard
command-line arguments available for all applications in the Strate suite.
=begin remainder of documentation here...
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