tobias_hofer,

Just a little trick on using 'print' statements and debugging. (Note: I'm using *nix boxes) At the beginning of all of my packages, I define (actually copy the code) the following:

######################################################################
+#
# DEBUG       ==0 {no debugging}, ==1 {debugging}, >=2 {greater debugg
+ing}
######################################################################
+##
#   our $Debug = 0; our $DLOG; ## Production
    our $Debug = 4; our $DLOG; ## Testing

    if ( $Debug )
    {  my $logFile = "MyLog_$$";      ##  Good for multi-user testing
       open($DLOG,">",$logFile) || die "Cannot open $logFile:$!";
       print $DLOG "############################# ".scalar localtime()
+."\nStart. . . \n";
    }
    else { open $DLOG, ">>", "/dev/null" ); }
[download]

At different places in the code, if I have something going wrong, I insert statements like:

    for my $key { sort keys %Hash )
    {   ... do something ...
        if ( $Debug >= 4 ) { print $DLOG "Hash:\t$key\t|$Hash{$key}|\n
+"; }
    }
[download]

Once you get it working, all you have to do to stop printing to the log, is change the '4' to a '5' and the print won't be executed. When computers were much slower than today, I used to take them out for production, but now I leave them in and change the global '$Debug' to '0'.

The advantage to doing this is if you have a production problem, you can turn the debugging on and get some help finding the problem. :-)

There have been times when I've had a debug statement after every line of code to figure out what was going wrong. It's usually a typo or some other simple mistake, but without the debug info, you just don't see it. ( I always use strict and warnings, but sometimes things get through. )

Always name the output so you can use your editor to search on the print statement. Notice that I put '|' around the variables to help see if it's undefined or "". You can also print to STDERR when your getting warnings. One time I was getting a couple 100K warnings for a script and by printing to STDERR, I was able to see the start and end of the problem in the loop. If your not testing a multi-user or multi-tasking package you don't need the '$$'. That's just so you don't have to lock/unlock the log file.

Good Luck...Ed

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