I had a consultant do some a work a couple of years ago and am now trying to solve a problem and I can't figure what this is doing:

...in program...
$MSG->trace( "my message");

...in module..
sub trace    { shift->_message( TRACE, @_ )   }
sub channels_by_fh    { map { $_->[0] } @{ shift->{handles} } }
sub channels_by_file  { () }
sub channels_by_email { () }
sub channels_by_level { grep { $_[0]->level( $_[1] ) } $_[0]->channels
+ }
    
sub _message 
    {
    my $self  = shift;
    my $level = shift;
        
    foreach my $channel ( $self->channels_by_level( $level ) )
        {
        print $channel $self->tag($level) . "@_" . "\n";
        }
    
    }

[download]

Right now I am getting an error message of "Can't locate object method "channels" via package..." which is pointed at the line "sub channels_by_level", I am self taught and don't understand what the subroutine is doing, I am not familiar with what grep does or which direction this lines is working. I am hoping someone can explain this for me.

g_White

In reply to I don't understand this grep by gwhite

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.