Re: [mv] Trouble getting piece of perl script working HELP!

[Kyle Hayes <kyle540@quicknet.net>]

See below...

On Fri, 24 Sep 1999, Jarno Niemela wrote:

> ******    message to minivend-users from Jarno Niemela <jargon@iki.fi>     ******
> 
> Hello.
> 
> I have following piece of perl code in my page, which I use
> to calculate bank reference numbers. But for the life of me I just cant
> get it working!
> 
> [perl scratch]
> $receipt_nr = '123456';      
> 
> @multipliers = (7,3,1);
> 
> if ($receipt_nr =~ /([0-9]*)/)
> {
>     $receipt_nr = $1;
> }

Careful here.  I think you really want:

if($receipt_nr =~ m/^([0-9]+)$/)...

What you have will match all the following:

TTTTT
1AAAA
a45564g

The '*' will let the expression match null.  Because you haven't anchored
the regular expression, it is free to find a match anywhere within the
$receipt_nr string.  Also, because you haven't anchored it to the end
(with the $) character, it will simply stop when it runs out of numeric
characters.  Thus '1AAA' will match and $1 will be '1'.

This regex stuff is very hard to get right.  I am always finding ways to
break my regexes :-(

If you think that the receipt number will contain characters other than
numbers, you can use tr/// to get rid of them:

$receipt_nr =~ tr/[0-9]//cs;

Check that before you try it, I can't remember if you need the brackets or
if the 'cs' modifier is correct.  After that call, $receipt_nr will only
contain numeric characters.

>         
> $i = (length $receipt_nr) - 1;

Length in Perl does not include a null termination character, so why the
-1?

> if ($i < 0 or $i > 20)
> {
>     exit;
> }
>
> @merkit = split //,$receipt_nr;
>          
> $k = 0;
> $sum = 0;
> 
> for ($j=$i; $j > -1;$j--)
> 
> {
>     if ($k == 3) { $k=0 };
>     
>     $sum = @merkit[$j] * @multipliers[$k] + $sum;
>     $k++;
> }
> 
> $tens = 0;
> 
> while ($tens <= $sum)
> {
>     $tens = $tens + 10;
> }
> 
> $checksum = $tens - $sum;
> 
> $bank_ref = join '',$receipt_nr,$checksum;
> $Safe{'scratch'}{'ref'}=$bank_ref;
> 
> [/perl]
> 
> When I run the same code as a normal perl script it works fine.
> 
> But on minivend it just doesn't work!
> 
> I try to output it using following tag
> Reference   : [scratch ref]
> 
> I'm using 
> Minivend 3.14-3
> Linux (Redhat 6.0)
> Perl 5.005_03
> Apache 1.39
> 
> If I try just some simple test routine, everything works fine.
> What I'm doing that minivend cant digest?
> 
> And does anyone know any alternative way of doing some calculating in
> minivend?
> For example calling external java program (I prefer java over perl)
> 
> 
> 
> Things I've tried
> 
> [perl args=sratch]
> 
> Following user tag in minivend.cfg
> 
> UserTag realperl   HasEndTag
> UserTag realperl   CanNest 
> UserTag realperl
> Interpolate
> UserTag realperl   Routine <<EOF
> sub {
>     my $str = eval {
> 
>     eval $_[0] or die;
>     };                        
> }
> EOF
> 
> and then 
> [realperl]
> [perl scracth]
> ....

Try making this a UserTag:

[checksum account='[value account]' ... ]

UserTag checksum ORDER account ...
UserTag checksum ROUTINE <<EOR
sub {
...
do calculations here
...
set scratch variable.
}
EOR

Within the UserTag, I think you use something like:

     $Vend->{'scratch'}->{'ref'} = $result;

You might have to look around in the code a little to get that correct...

Some of the Perl seems like it might not be doing what you want.  It may
work for you hard-coded value, but it might not for other things.

I have never had much luck with scratch variables.  Probably I am just
missing some important point.  However, I have used 'value' variables with
much success.

Best,
Kyle (KH)