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Re: Getopt::Long good style? (tight scoping)

by grinder (Bishop)
on Jul 28, 2004 at 13:17 UTC ( #378024=note: print w/ replies, xml ) Need Help??


in reply to Getopt::Long good style?

I have no problems with the anonymous sub. I do take issue, though, with the list of scalars for options. I much prefer to use a hash to keep things in one place.

But hang on! If you mispell a scalar, the compiler will bark at you. If you mispell a hash key, the runtime will autovivify it for you. Hmm.

But that's ok too, because what I really prefer doing is hiding it all away in a scope, and declaring subs as The Only Way of retrieving values. Admittedly, you still don't get a compile time error, but it will blow up at runtime if you get things worng. My template looks something like:

{ use Getopt::Long; my %opt; GetOptions ( \%opt, qw/ verbose! file:s debug+ help/ ) || die sub { print <<END_OF_HELP; $0: you blew it! Switches are as follows: --help | -h this help screen ... END_OF_HELP } sub debug { exists $opt{debug} ? $opt{debug} : 0 } sub verbose { exists $opt{verbose} ? 1 : 0 } sub file { if( not exists $opt{f} ) { '' } elsif( not defined $opt{f} ) { '/etc/passwd' } else { $opt{f} } } }

The sub file lets you distinguish between an argument that is absent (return an empty string), present, but with no value (return a fixed name) or present with a value (return the value).

Since the %opt hash isn't available outside the scope, the program can't (accidentally or on purpose) modify the contents. This may be construed as a feature.

- another intruder with the mooring of the heat of the Perl


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