I already knew that 'use strict;' is a Good Thing ™, but searching on Perlmonks.org has taught me to use it from the beginning, and not as an afterthought. However, I do not see an answer to my question.

I wrote the following module, not intending to re-invent the wheel, but to practice writing modules. The problem is this: when I uncomment the 'use strict;' line, there aren't any errors -- the code simply doesn't work.

This simple module provides timestamps that have configurable (more or less UNIX style) formats. The user tie's the class to a scalar; assigning a format string to the scalar results in the instance using the supplied format until it is undef'ed or assigned again. Reading from the scalar produces the timestamp string. Here's the module code:

package TimeStamp;
#use strict;
use Carp;

my @a = qw(Sun Mon Tue Wed Thu Fri Sat);
my @A = qw( Sunday Monday Tuesday Wednesday Thursday Friday Saturday);
my @b = qw(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec);
my @B = qw(January February March April May June July August September
+ October November December);
my @meridian = qw( AM PM );

# KEY TO FORMAT TOKEN CODES
# %a:short day of week, %A:long day of week, 
# %b:short month, %B:long month, %d:day of month,
# %D: date, %X:time (24 hour), %x: time (12 hour), 
# %y:short year, %Y:long year

sub a { $a[$_[6]] }
sub A { $A[$_[6]] }
sub b { $b[$_[4]] }
sub B { $B[$_[4]] }
sub d { &pad($_[3]) }
sub D { &pad(1 + $_[4]) . "/" . &pad($_[3]) . "/" . &pad($_[5] - 100) 
+}
sub X { my ($ss,$mm,$hh) = map { &pad($_) } @_; "$hh:$mm:$ss" }
sub x { my ($ss,$mm,$hh) = map { &pad($_) } @_;
        ($hh>12) ? $hh-12 . ":$mm:$ss $meridian[1]" : "$hh:$mm:$ss $me
+ridian[0]"; }
sub y { &pad($_[5] - 100) }
sub Y { $_[5] + 1900 }

# &pad() will add a leading zero to single digits. 

sub pad {
    my @result = map {($_ < 10) ? "0$_" : $_} @_;
    return wantarray ? (@result) : $result[0];
}

sub TIESCALAR {
    return (bless { fmt => \"%a %D %X" }, shift);
}

sub FETCH {
    my $obj = shift;
    my @time = localtime;
    my $fmtString = ${$obj->{fmt}};
    my @tokens = split /(%\w)/, $fmtString;
    my $result = "";
    for ( @tokens ) {
        if ( /\%./ ) {
            s/\%//;
            eval {
                $result .= &{$_}(@time);
            };
            next if ($@);
        } else {
                $result .= $_;
        }
    }
    return $result;
}

sub STORE {
    my ($obj, $fmt) = @_;
    $obj->{fmt} = \$fmt;
}

1;

[download]

And here's a test script:

#!/usr/bin/perl
use strict;
use warnings;

use TimeStamp;
my $ts;
tie $ts, 'TimeStamp';

print $ts, "\n";

$ts = "%A, %B %d, %Y";
print $ts, "\n";

$ts = "Day %d in the month of %B, the year %YAD";
print $ts, "\n";

my $ts2;
tie $ts2, 'TimeStamp';

$ts = "%D %x";
$ts3 = "%D";

print $ts2, "\n";
print $ts, "\n";

[download]

The output with 'use strict;' commented out in the module:

C:\>perl -w ts_test.pl 
Tue 10/29/02 20:07:48
Tuesday, October 29, 2002
Day 29 in the month of October, the year 2002AD
10/29/02
10/29/02 8:07:48 PM

[download]

and the output with 'use strict;' uncommented in the module:

C:\>perl -w ts_test.pl 
  
,  , 
Day  in the month of , the year AD

[download]

It seems that the module's format subroutines become inaccessable with 'use strict;' enabled.

This is ActivePerl 5.6 on Win2000 Pro.



PCS

In reply to Puzzled about strict by webengr

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