Using perl's runtime options with -Mstrict

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

Greetings, Monks.

I was recently turned on to perl -s as a way to parse command line options (please, I dont want to know about any more command line options modules, its way overkill).

So, without further ado, from perldoc perlrun:

       -s   enables rudimentary switch parsing for switches on
            the command line after the program name but before
            any filename arguments (or before a --).  Any switch
            found there is removed from @ARGV and sets the
            corresponding variable in the Perl program.  The
            following program prints "1" if the program is
            invoked with a -xyz switch, and "abc" if it is
            invoked with -xyz=abc.

                #!/usr/bin/perl -s
                if ($xyz) { print "$xyz\n" }
[download]

So I am taken to understanding that I can then use an option from the command line to have $xyz (or $switch, as used in the example below) defined.

Here's a relevant example:

#!/usr/bin/perl -ws
# minus-ess.pl

use strict;

# if we run it ./minus-ess.pl -switch "foo" it should be defined. 
my $switch = "hooray" unless (defined $switch);

print $switch;
[download]

which yields us:

Global symbol "$switch" requires explicit package name at minus-ess.pl
+ line 7.
[download]

I guess then what I need to do is "turn off" strict while I am parsing the command-line options. My idea was to use an anonymous code block ( { ... } ) turn off strict in there, and then just close it.

thanks,
dep.
--
i am not cool enough to have a signature.

Comment on Using perl's runtime options with -Mstrict Select or Download Code

Replies are listed 'Best First'.
(tye)Re: Using perl's runtime options with -Mstrict by tye (Sage) on Jan 27, 2001 at 03:29 UTC
-s is for one-liners (and even then isn't very useful). -Mstrict is not for one-liners. The two are pretty much completely incompatible. However, you could just write: `#!/usr/bin/perl -ws use strict; # My supported command-line switches: use vars qw( $switch $help $debug $foo ); $switch= "hooray" unless $switch;` [download] I see no reason to have a global $switch that Perl creates and then have a different, same-named lexical that you create with my. Note that anyone using your script can accidentally type `minus-ess -snitch -helf -debung -food` [download] and your program will silently act just like they hadn't included any command-line switches (that is, unless your program also defines a global named, for example, $food, and then relies on it to be initially uninitialized). In other words, I don't consider this even close to a good design decision. ): - tye (but my friends call me "Tye")	[reply] [d/l] [select]
Re (tilly) 1: Using perl's runtime options with -Mstrict by tilly (Archbishop) on Jan 27, 2001 at 04:27 UTC
Expanding on what tye said, you are wandering in very dangerous territory with your construct. First of all your construct is wandering into the `my $foo if 0` bug. Secondly if your user mistypes the command line ever so slightly then neither you nor they get a chance to catch that fact. Thirdly you do not have any chance to choose to have certain options take arguments. I generally rectify all of these with Getopt::Std. If you want longer option names, you can use Getopt::Long instead. (It has a significantly more complex interface though.) Both are part of the standard distribution..	[reply]


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