CODEWITHSUNDEEP
perlarguments
SVGK Raju
SVGK Raju

Reputation: 49

Not able to restrict the number of arguments for an option with GetOptions in Getopt::Long

My program is as follows:

   use strict;
   use warnings;

   use Getopt::Long;

   my @letters;
   my @words;

   GetOptions(
      "letters=s{2}" => \@letters,
      "words=s{,}" => \@words
   );

   print "Letters: " . join(", ", @letters) . "\n";
   print "Words: " . join(", ", @words) . "\n";

When I run this program I get the output as follows:

   perl getopts.pl --letters a --words he she it
   Letters: a, --words
   Words:

--words is read as part of --letters arguments itself. I expect GetOptions to throw error message in this scenario. How to get this done.

Upvotes: 0

Views: 237

Answers (2)

Axeman
Axeman

Reputation: 29854

A quantifier of '{2}' means "exactly two". So, it's even ignoring the second argument afterwards is a switch.

The GetOpt::Long text that you probably took this from:

GetOptions( 'coordinates=f{2}' => \@coor, 'rgbcolor=i{3}' => \@color );

Are specific conditions for which pairs and triads make sense. You want an x and a y coordinate, or you want a value for each part of an RGB specification. Just the way that you would expect 'cmykcolor={4}'.

If you want at least one, up to the next switch, you can specify '{1,}' as your quantifier, and if you want "at most two", then '{1,2}' makes sense. Interestingly enough, the behavior of '{,2}' is exactly the same as '{1,2}'. It seems that as long as you specify a quantifier, it will suck up one more argument, regardless of whether or not the next argument is a switch.

So the quantifiers in Getopt::Long may look the same as regex, but they mean different things.

Upvotes: 2

JRFerguson
JRFerguson

Reputation: 7516

Change:

"letters=s{2}" => \@letters,

to:

"letters=s{1,2}" => \@letters,

...which allows 1-to-2 letters as the argument.

Upvotes: 6

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