Perl syntax

Shell Programming and Scripting
1

what does the below syntax.

sub read {
    my $file = shift;
    my (%lookup, %max);
    open IN, $file or die "Unable to open $file: $!";
    while (<IN>) {
        chomp;
        my ($level, $comm, $parent, $comm_desc) = split /\t/;
        $lookup{$level}{$comm_desc} = [$parent, $comm];
        $max{$level} = $comm  if ( ! defined $max{$level}  or $max{$level} < $comm );
    }
    close IN or die "unable to close $file: $!";
    return (\%lookup,\%max);
2

Hello,

Firstly: welcome to the forum. Secondly: I'm afraid it's not too clear what you really mean, here. You appear to be asking about the syntax of the code block provided. Well, to my eyes, it certainly looks like valid Perl syntax, generally speaking (apart from missing a closing curly brace at the end). The syntax of a language refers to the "grammar" of it, so to speak, and doesn't say anything on its own about what a given script does, or even whether or not it will work for its intended purpose.

What, precisely, is it that you want to know ? What problem do you actually have, or what problem are you trying to solve ? Also, please provide full information about the nature of your environment (e.g. the operating system, distribution, version, hardware architecture and shell, at a minimum; and for programming languages, what version of the programming language you're using in addition to the above). Once we have this information, we may be able to assist you further.

3

Hey nmkl,

As a starter, this appears to be part of a module (overwriting the native read function only makes sense in this context)

Could you provide details on the module, an example of the data source it's usually instantiated with and if the read function is used exclusively within the module or if it is also used as part of the interface?

The function itself reads a tab separated file into a data structure and captures a max for one of the values for each "level".

However to fully explain its operation more context would be needed.