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

# Dear Monks,
#
use strict;
subroutine(10);
subroutine(20);

sub subroutine
{
    my $param = shift;


   #Starting with this
    printf "package=%s file=%s line=%s param=%d\n",caller(),$param;

   #Is there a more elegant way to skip the package=%s parameter:
    printf 'file=%2$s line=%3$d param=%4$d %5$s',caller(),$param,"\n";

   #Such as a % command that would eat the given parameter?
    printf "%Zfile=%s line=%s param=%d\n",caller(),$param;
}

[download]

Replies are listed 'Best First'.
Re: Skipping parameters in sprintf %, elegantly
by ambrus (Abbot) on Aug 19, 2008 at 19:11 UTC

    But to make your code self-documenting, the best practice might actually be 

    my($package, $file, $line) = caller();
sprintf "file=%s line=%s param=%d\n", 
        $file, $line, $param;

    [download]
[reply]
[d/l]
Re: Skipping parameters in sprintf %, elegantly
by kyle (Abbot) on Aug 19, 2008 at 18:30 UTC 
    printf "file=%s line=%s param=%d\n", (caller())[1,2], $param;

    [download]
[reply]
[d/l]
Re: Skipping parameters in sprintf %, elegantly
by ambrus (Abbot) on Aug 19, 2008 at 18:56 UTC

    Yes, "%.0s"

[reply]
[d/l]
      Perfect! Thanks.
[reply]
Re: Skipping parameters in sprintf %, elegantly
by psini (Deacon) on Aug 19, 2008 at 19:00 UTC

    In sprintf you can specify for each command the position in the list from which the value must be taken. I think this is a feature present from v.5.8, not sure...

    In your example you can do:

    printf "file=%2\$s line=%3\$s param=%4\$d\n",caller(),$param;

    to skip the first parameter.

    Rule One: "Do not act incautiously when confronting a little bald wrinkly smiling man."

[reply]
[d/l]
Re: Skipping parameters in sprintf %, elegantly
by gone2015 (Deacon) on Aug 19, 2008 at 18:44 UTC

    Array slicing, eg:

       printf "l=%s p=%s f=%s", (caller)[2, 0, 1] ;

    [download]

[reply]
[d/l]

      (caller)[2, 0, 1] is a LIST SLICE not an array slice, there is no array there.

[reply]
[d/l]

        I regret that the distinction between an ARRAY and a LIST in Perl is lost on me :-(. I humbly beg that you initiate me into this mystery.

[reply]
Re: Skipping parameters in sprintf %, elegantly
by ambrus (Abbot) on Aug 19, 2008 at 19:02 UTC

    Alternately "file=%2\$s line=%3\$s param=%4\$d\n". Note that the indexing starts by 1.

    Update: fixed typo in code where one of the \$ was \% instead.

[reply]
[d/l]
[select]

Back to Seekers of Perl Wisdom