Perl：使用GetOptions进行命令行处理

Question

Problem: I've got a script that can be called in one of the following ways:

./script.pl -a
./script.pl [-w] -<i|d|r|t>

Meaning, the -w flag is optional, but either -i or -d or -r or -t must be specified.

If the user doesn't call the script in any of those ways, the function usage should be called.

My attempt:

sub fInv
{
    print "fInv"."\n";
}

sub fDisp
{
    print "fDisp"."\n";
}

sub fRanking
{
    print "fRanking"."\n";
}

sub fTickets
{
    print "fTickets"."\n";
}

sub usage
{
    print "Usage shown here.\n";
}

%options = (i => \&fInv, d => \&fDisp, r => \&fRanking, t => \&fTickets);

$write = 0;

GetOptions("a" => \&usage)
    or GetOptions("w" => \$write,
                    keys($options) => \&options) # This is clearly wrong
    or die usage;

Answer 1

Doesn't make much sense to have 5 variables to represent one choice.

my $type;
my $opt_w;

my $set_type = sub {
   my ($new_type) = @_;
   die "-$type and -$new_type cannot be used together\n"
      if defined $type && $new_type ne $type;
   $type = $new_type;
};

GetOptions(
   'help|h|?' => \&help,
   ( map { $_ => $set_type } qw( a i d r t ) ),
   'w' => \$opt_w,
)
   or usage();

usage("One of -a, -i, -d, -r or -t must be specified\n")
   if !defined($type);

usage("-w cannot be used with -a\n")
   if $opt_w && $type eq 'a';

---

sub help {
    print "...detailed help...\n";
    exit(0);
}

sub usage {
    print(STDERR $_[0]) if @_;
    print(STDERR "usage: script -a\n");
    print(STDERR "       script [-w] {-i|-d|-r|-t}\n");
    print(STDERR "Use script --help for more information\n");
    exit(1);
}

Answer 2

Basically, use all of the various options and test the combinations you want.

use strict;
use warnings;
use Getopt::Long;
use Pod::Usage;      # Learn something new!


my ( $opt_a, $opt_i, $opt_w, $opt_d, $opt_r, $opt_t, $opt_w );
GetOoptions {

     a    => \$opt_a,
     i    => \$opt_i,
     w    => \$opt_w,
     d    => \$opt_d,
     r    => \$opt_r,
     t    => \$opt_t,
     help => \$help,
} or die pod2usage ( -message => "You did it wrong" );

if ( $help ) {
    pod2usage;
}

if ( $opt_a and ( $opt_w or $opt_d or $opt_r or $opt_t ) ) {
    pod2usage ( -message => "Either use '-a' by itself, or the other parameters" );
}

if ( not ( $opt_w and $opt_w and $opt_d and $opt_r and $opt_t ) {
pod2usage ( -message => "You need to use parameters -d, -i, -r, or -t")

#
# And now to your regularly scheduled program
#

However, I would recommend you going long , that is with parameter names. By default, Getopt::Long will allow for parameter abriviations. If -i is for integer , ( I don't know, you didn't give too many clues to what these parameters mean), go ahead and specify -integer as a parameter (and use $integer instead of $opt_i ). Users can abbreviate -integer as -i since no other parameter starts with -i . You could also use aliases too:

 "divider|i" => \$divider,

Then, a user could use -divider or -i as the parameter.

Now to this Pod::Usage...

Perl has a documentation system called POD (it stands for Plain Old Documentation ). It's rather simple to pick up, and it allows you to add documentation right into your program.

=pod

=head1 NAME

script.pl

=head1 SYNOPSIS

    ./script.pl -a

or

    ./script.pl [-w] -<i|d|r|t>

=head1 DESCRIPTION

blah, blah, blah, yadda, yadda, yadda

=head1 OPTIONS

You can see this documentation by using the perldoc command which comes with Perl:

$ perldoc script.pl

This will print out your POD in full glory. If anyone needs to know how to use your program and what it does, it's right there.

Pod::Usage will by default print out the Synopsis section of your POD and then exit. It's great when a user put the wrong option, or types script.pl -help .

There are many options. For example, you can print out the Synopsis and the Options section, or the entire POD, or selected bits and pieces.

It is a great way to document your code, and should be encouraged by everyone.

The only issue I had is that the documentation on the POD documentation doesn't specifically mention that command paragraphs (the lines that start with an equal sign) must have a blank line before and after them.