Using arguements and defaults

sock has asked for the wisdom of the Perl Monks concerning the following question:

This is my first script. I created it to change any files that have the '_' character to a single space in a given directory. I'm using regex to select the files and a simple foreach statement to sift through the given files but how would i be able to pass arguments and have defaults for those not passed?
~ Nick

#!/usr/bin/perl -ws
use strict;
my $oggdir = '/media/tmp/';
chdir $oggdir or die "can't chdir to $oggdir: $!\n\n";
opendir(DIR, $oggdir) or die "can't open $oggdir for read: $!\n\n";
my @files = grep { /.*_+.*\.[Oo][Gg]{2}$/ } readdir(DIR);
closedir(DIR) or warn "error closing $oggdir: $!\n\n";

foreach ( @files ) {
  my @chars = split(/_+/, $_);
  my $final=join(" ", @chars);
  print "Original: $_ \n";
  print "New: $final \n";
  rename $_, $final;
  print "Conversion Complete.\n";
}
[download]

Comment on Using arguements and defaults Download Code

Replies are listed 'Best First'.
Re: Using arguements and defaults by Roger (Parson) on Nov 24, 2003 at 05:52 UTC
Do you mean pass command-line arguments? If so, checkout the module Getopt::Long. Otherwise, are you looking for something like below? `#!/usr/bin/perl -w use strict; use IO::Dir; my $oggdir = '/media/tmp/'; ParseDirectory($oggdir); sub ParseDirectory { my $dir = shift; my $d = IO::Dir->new($dir) or die "Can not open directory $dir for read!"; while (defined(my $f = $d->read)) { if ($f =~ /._+.\.[Oo][Gg]{2}$/) { # matching files my $new_name = $f; $new_name =~ s/_//; # remove _ # rename $f to $new_name, etc. } else { # non-matching files # do whatever, set to default, etc. } } }` [download] And an example of using Getopt::Long to parse command-line arguments: #!/usr/local/bin/perl -w use strict; use Getopt::Long; # Parse command line arguments and assign corresponding variables GetOptions ( 'i\|init=s' => \( my $INIT = undef ), # Specify the root director +y 'u\|upload' => \( my $UPLOAD = undef ), 'v\|verbose' => \( my $VERBOSE = 0 ), ); unless ( defined $INIT ) { print <<EOF Kapiti Exception Report Usage: $0 [options] Options: -i\|--init [file] Specify the path to initialization file -u\|--upload Upload the result into database -v\|--verbose Let the report generator print more information EOF ; exit(1); } # continue on... [download]	[reply] [d/l] [select]
Re: Using arguements and defaults by sgifford (Prior) on Nov 24, 2003 at 05:49 UTC
Arguments are in the list `@ARGV`. So if you want to set `$oggdir` to the first argument, or to `/media/tmp` if there is no first argument, you could do something like: `my $oggdir; if ($ARGV[0]) { $oggdir=$ARGV[0]; } else { $oggdir='/media/tmp'; }` [download] A shorter and more idiomatic way to do the same thing is: `my $oggdir = shift \|\| '/media/tmp';` [download] `shift` removes the first item from a list and returns it; in the main body of a program (outside of subs), it defaults to using `@ARGV`. So this is a little different than the above; it will remove the first argument from `@ARGV`. If `shift` returns an argument, `$oggdir` will be set to it; otherwise it will use the other half of the or, and set it to the default value. If you want more complex argument processing, try using `Getopt::Std` or `Getopt::Long`.	[reply] [d/l] [select]
Re: Using arguements and defaults by vladdrak (Monk) on Nov 24, 2003 at 06:13 UTC
How about something like: `#!/usr/bin/perl use strict; # @ARGV is = to @_ by default my $path=shift or die "Usage: $0 <directory\|file>\n"; # Is it a directory or a file? if (-d $path) { opendir(DIR,$path) or die "could not open $path: $!\n"; for my $file (readdir(DIR)) { if ($file =~ /\_/) { nounder($file); } } closedir(DIR); } else { nounder($path); } sub nounder { my $file=shift; my $newfile=$file; $newfile=~s/\_/ /g; rename($file,$newfile) or die "couldn't rename $file: $!\n"; print "renamed $file to $newfile\n"; }` [download] -vladdrak	[reply] [d/l]
Re: Re: Using arguements and defaults by holo (Monk) on Nov 24, 2003 at 06:30 UTC
@ARGV is != to @_! It's just that shift works differently in the main file's scope. See perldoc -f shift and perldoc perlvar.	[reply]
Re: Using arguments and defaults by Roy Johnson (Monsignor) on Nov 24, 2003 at 17:49 UTC
Just a couple of notes: `/._+.\.[Oo][Gg]{2}$/` [download] should probably be `/_+.*\.ogg$/i` [download] And your use of `split` and `join` to replace the _ would be better done with `tr/_/ /s;` [download]	[reply] [d/l] [select]


Come for the quick hacks, stay for the epiphanies.
	PerlMonks