Perl Intro 9 Command Line Arguments

Perl Intro 9 Command Line Arguments

• 1.
  Perl Brown Bag Command Line Arguments Shaun Griffith May 8, 2006 05/13/12 ATI Confidential 1
• 2.
  Agenda TIMTOWTDI •Argument Types •DIY (DoIt Yourself) •-s Builtin •Getopt::Long •Getopt::Declare 05/13/12 2
• 3.
  Argument Types What kindsof arguments to expect? -xyz toggle switch -xyz 17 value -xyz=17 value (parsing) -wx combined (-w –x) -x 17 24 list --x turn off --long double dash value bare value -- end of arguments Where are the arguments? @ARGV 05/13/12 3
• 4.
  Criteria for Solution? Whatdo we want a solution to accomplish? • Easy to use • Argument validation • integers • file names • Self-documenting • Usage statement (help) • Flexible • Powerful 05/13/12 4
• 5.
  Do It Yourself Handlearguments manually while (@ARGV) { my $argv = shift(@ARGV); if ($argv =~ /^-x$/){$x=1;next} if ($argv =~ /^-y$/) { $y = shift(@ARGV) or die; next; } if ($argv =~ /^--$/) { last } # stop push @files, $argv; } @ARGV = (@files, @ARGV); while (<>) { do something here } Pros: full control Cons: tedious, check arguments manually documentation? extensibility? 05/13/12 5
• 6.
  -s Option Perl hasa builtin option for basic argument handling: -s In the script, use it on the shebang line: #!/usr/local/bin/perl –s …enabling this behavior: Option Variables -xyz $xyz = 1 -xyz=blue $xyz = “blue” Pros: easy Cons: documentation? shebang combined options? check arguments manually 05/13/12 6
• 7.
  Getopt::Long use Getopt::Long; my $data= "file.dat"; my $length = 24; my $verbose; $result = GetOptions ( "length=i" => $length, # numeric "file=s" => $data, # string "verbose" => $verbose # flag ); Pros: argument checking Cons: 24 pages of docs for G:L script documentation? wordy 05/13/12 7
• 8.
  Getopt::Declare use Getopt::Declare; my $spec= qq{ [nocase] # case insenstive options -in <in:if> input file -out <out:of> output file [mutex –in –out] -off <offset:i> offset (int) -b[ells+]w[histles] -bw also works { $::BELLS = 1; } } my $options = Getopt::Declare->new($spec); Pros: Functionality! Spec is usage Argument checking Full Parser! Cons: Functionality! 32 pages of docs for G:D! Subtle gotchas (like []) Object oriented (more work?) 05/13/12 8
• 9.
  Next Time? Suggestions? 05/13/12 9