Wako has asked for the wisdom of the Perl Monks concerning the following question:

I am writing a script to convert PMMail2000 .msg files into one .mbx file. I am fairly new to perl, but I've managed to mostly get something that comes close to working, but I do not understand why in the following snippet of code 
for ($j=2; $j<=$message_count+1;$j++){
                print "\>$unixfrom\n";
                print "$return_path[$j]\r";
        print "$received[$j]\r";
        print "$date[$j]\r";
        print "$from[$j]\r";
        print "$to[$j]\r";
        print "$subject[$j]\r";
        print "$message_id[$j]\r";
        print "$mimeversion[$j]\r";
        print "$content_type[$j]\r";
        print "$xstatus[$j]\r";
        print "$xkeywords[$j]\r";
        print "$xuid[$j]\r";        
        }

[download]
print "\>$unixfrom\n"; works and prints what is expected, but print "\>$unixfrom\r"; does not work at all. All/most of the rest of the lines print correctly with \r as well.... Any ideas? Is \r the correct character to end a line with for an mbx file? Thanks!

Replies are listed 'Best First'.
Re: Print Question
by Zaxo (Archbishop) on May 18, 2003 at 02:44 UTC

    It is most portable to rely on $/ or "\n". "\r" is incorrect in unix.

    It is often helpful to bracket variables in interpolating quotes like so:     print ">${unixfrom}\n"; which allows a construction like "\>${unixfrom}foo\n" in concatenation.

    It would be good to print a list of arguments instead of constructing a sequence of print statements. 

    {
    local $, = "\n";
    print '>' . $unixfrom,
          $return_path[$j],
          $received[$j],
          $date[$j],
          $from[$j],
          $to[$j],
          $subject[$j],
          $message_id[$j],
          $mimeversion[$j],
          $content_type[$j],
          $xstatus[$j],
          $xkeywords[$j],
          $xuid[$j];
}

    [download]
    That will save some unneeded churning around with interpolation. The print function stringifies its arguments by default, so interpolating quotes are unnecessary.

    After Compline,
    Zaxo

[reply]
[d/l]
[select]

      I'd write this as

       print '>', $unixfrom, join("\n",
           $return_path[$j],
           $received[$j],
           $date[$j],
           $from[$j],
           $to[$j],
           $subject[$j],
           $message_id[$j],
           $mimeversion[$j],
           $content_type[$j],
           $xstatus[$j],
           $xkeywords[$j],
           $xuid[$j]);

      [download]
      . That is, to me, much more clear then using the semi-magical $,.

      Warning: Unless otherwise stated, code is untested. Do not use without understanding. Code is posted in the hopes it is useful, but without warranty. All copyrights are relinquished into the public domain unless otherwise stated. I am not an angel. I am capable of error, and err on a fairly regular basis. If I made a mistake, please let me know (such as by replying to this node).

[reply]
[d/l]
[select]
Re: Print Question
by The Mad Hatter (Priest) on May 18, 2003 at 03:01 UTC
    Somewhat off topic, but whenever you have multiple arrays that describe the same thing, you should probably make it a hash of hashes instead. Something like this would be better and easier to deal with: 
    %messages = (1 => { unixfrom        => "blah",
                    return_path     => "foo@bar.com",
                    received        => "blorg",
                    date            => "another date",
                    from            => "bar@foo.com",
                    to              => "you@me.com",
                    subject         => "Spam Me Senseless!",
                    message_id      => 42,
                    mimeversion     => "text/plain",
                    content_type    => "text/plain",
                    xstatus         => "foop",
                    xkeywords       => "spam trash garbage",
                    xuid            => 13
                  }
             );

    [download]
    With a hash, the key represents the message and could either be any unique value, or possibly even the message_id (if it is unique). Printing it out is then just a matter of looping through the keys, retrieving the values, and printing them.
[reply]
[d/l]
[select]

      (Or you could use an array of hashes, and have the indeces be the same as what you're using now.)

      Warning: Unless otherwise stated, code is untested. Do not use without understanding. Code is posted in the hopes it is useful, but without warranty. All copyrights are relinquished into the public domain unless otherwise stated. I am not an angel. I am capable of error, and err on a fairly regular basis. If I made a mistake, please let me know (such as by replying to this node).

[reply]

        wouldn't an array of hashes be a bit of a waste of memory in this case?

        cheers,

        J

[reply]

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