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References: <4EA9EE9C-5049-4C50-B361-07F58FA19896@langille.org>,
 <CALSf6fQ+iaXrz9bCe7mZEz8K+UsbG5jdgibueNK_dyhMUY2xdg@mail.gmail.com>
From: "Chris H" <bsd-lists@bsdforge.com>
Subject: Re: perl isvaliddate function
Date: Mon, 27 Oct 2014 09:17:20 -0700
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On Sat, 25 Oct 2014 13:21:35 -0500 "B. Estrade" <estrabd@gmail.com> wrote
> On Sat, Oct 25, 2014 at 11:56 AM, Dan Langille <dan@langille.org> wrote:
> 
> > I’m coding up a sanity check for FreshPorts.  It will verify that field
> > that should be dates are dates.
> >
> > Feedback welcome.  The system is already using the DATE module, so I’m
> > leveraging that.
> >
> > Pasted at http://dpaste.com/1H0Q8RR.txt but included below, because.
> >
> > $ cat test-date.pl
> > #!/usr/bin/perl
> >
> > use Date::Parse qw( str2time );
> >
> > sub IsValidDate($) {
> >   my ($string) = @_;
> >
> >   my $Date = str2time($string);
> >
> >   return defined($Date);
> > }
> >
> > my $a = '2014-11-30 unless *coin ports remain unfixed';
> >
> > if (IsValidDate($a)) {
> >   print "'$a' is a valid date\n";
> > } else {
> >   print "'$a' is NOT a valid date\n";
> > }
> >
> > my $b = '2014-02-30';
> >
> > if (IsValidDate($b)) {
> >   print "'$b' is a valid date\n";
> > } else {
> >   print "'$b' is NOT a valid date\n";
> > }
> >
> > my $c = '2014-02-28';
> >
> > if (IsValidDate($c)) {
> >   print "'$c' is a valid date\n";
> > } else {
> >   print "'$c' is NOT a valid date\n";
> > }
> >
> >
> > $ perl test-date.pl
> > '2014-11-30 unless *coin ports remain unfixed' is NOT a valid date
> > '2014-02-30' is NOT a valid date
> > '2014-02-28' is a valid date
> > $
> >
> > —
> > Dan Langille
> >
> >

> Looks fine to just get it working. If you wanted to be more efficient, I
> believe there is a way to use the core POSIX::strfmtime in a way that would
> verify that the date you start with is the same date as the one returned
> after the format.  This core function is also very useful for date addition
> and subtraction.
> 
> I don't have time at this moment to create a proof of concept, but if
> you're interested let me know and I will when I have a minute.
> 
> Cheers,
> Brett
> 
I also felt inclined to recommend POSIX::strfmtime.
I also thought you might save some cycles modifying your conditional from:

if (IsValidDate($b)) {
   print "'$b' is a valid date\n";
 } else {
   print "'$b' is NOT a valid date\n";
}

to:

unless (IsValidDate($b)) {
   print "'$b' is NOT a valid date\n";
}

you could even introduce

my $ok = "Everything looks AOK";

at the beginning, and revise your whole script to close with
the $ok, unless any of the 'unless' s fired.

Just my 2¢. :)

--Chris

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