The special variable '$.' is convenient when you want a quick way to detect the line number of the currently read file. But it can get a little confusing when you're dealing with multiple input files. In such cases, it might be advisable to take advantage of the added control and comfort of an object-oriented interface to filehandles such as that provided by IO::File.

IO::File inherits from IO::Handle and IO::Seekable. And one of the methods of IO::Handle is: input_line_number(), which happens to be an object-encapsulated substitute for '$.', but benefitting from all the scoping that applies to object instances.

A usage example:

use strict;
use warnings;
use IO::File;

{
    my $fh = IO::File->new( '< filename.txt' );
    if( defined $fh ) {
        while( my $line = <$fh> ) {
            print $fh->input_line_number(), 
                  ":\t",
                  $line;
        }
    }
}   # As $fh falls out of scope it is closed automatically.

[download]

It seems that input_line_number() is probably somewhat of a misnomer. Given that the input record separator needn't be '\n', the method would probably be better named input_record_number(), but that's just water under the bridge. :)


Dave

In reply to Re: Localization gotcha? by davido
in thread Localization gotcha? by benizi

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