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Brother frankus,

Perl does not force you to OO. You have to decide one day to cross the threshold and find out what's in it for you.

So, let me stick my neck out. I'm not crazy about objects, in Perl or otherwise. I just use them.

In my experience, Perl objects are good for structuring any program, from the lowly quick hack to a large application involving tens of modules, other people's and your own.

IMO, all those classical OO benefits show up more often than not in the programmer's daily work - the bread that our sandwiches are made of, so to speak

bundling the code and data together
encapsulating the data
managing object instances, each with it's state properly initialized and maintained
abstraction
separating interface from implementation
reusable modules
easy testing of modules

Let me give you an example - a quick hack I did last night.

I wanted to have a simple probe for the quantity of memory that my perl program is hogging at different phases of execution. I looked around for a Win32 module that could help me, and I found two - IProcess and Win32::PerfLib. I installed the former, tried the test scripts that came with it, and then simplified one of scripts and packed it into a module.

Here is my test script - just to exercise my module

#! perl -w
# TestPerlprocdata.pl 

use Perlprocdata;

my $pp = new Perlprocdata;

my @x;
for (0..5) {
    $pp->printProcessMemInfoShort; # probe
    # gobble some memory
    push @x, 1 for (0...100000);
    sleep 1;
}

# free the memory (to perl, not to the OS)
@x = ();


for (0..10) {
    $pp->printProcessMemInfoShort;  # probe
    # gobble some more memory
    push @x, 1 for (0...100000);
    sleep 1;
}

# free the memory (to perl, not to the OS)
@x = ();


__END__

           [Name] [PageFaults/s]    [PeakWS]        [WS]

         perl.exe            841     3436544     3436544
         perl.exe           1366     5586944     5586944
         perl.exe           1894     7753728     7753728
         perl.exe           2694    11034624    11034624
         perl.exe           2945    12062720    12062720
         perl.exe           3344    13697024    13697024
         perl.exe           4545    18620416    18620416
         perl.exe           4545    18620416    18620416
         perl.exe           4545    18620416    18620416
         perl.exe           4545    18620416    18620416
         perl.exe           4545    18620416    18620416
         perl.exe           4545    18620416    18620416
         perl.exe           4545    18620416    18620416
         perl.exe           4647    19038208    19038208
         perl.exe           5046    20676608    20676608
         perl.exe           5444    22306816    22306816
         perl.exe           5844    23949312    23949312
[download]

And here is my quick and dirty module:

#! perl -w
# Perlprocdata.pm by Rudif@bluemail.ch

use strict;

package Perlprocdata;


# uses Win32::IProcess by Amine Moulay Ramdane                
# from website: http://www.generation.net/~aminer/Perl/ 


use Win32::IProcess qw(
    PROCESS_QUERY_INFORMATION PROCESS_VM_READ INHERITED INHERITED DIGI
+TAL NOPATH
);  


#----------------------------------------------------------
sub new {
    my ($class, %args) = @_;
    my $self = {};
    bless $self, $class;

    my $obj = $self->{obj} = new Win32::IProcess || die "Can not creat
+e an IProcess object..\n";

    my @EnumInfo;
    $obj->EnumProcesses(\@EnumInfo);

    my $size=scalar(@EnumInfo);

    for(my $j=0;$j<$size;$j++) {
        if ($EnumInfo[$j]->{ProcessName} =~ /perl/i) {
            $self->{EnumInfo} = $EnumInfo[$j];
            my $Info;
            $obj->GetProcessMemInfo($EnumInfo[$j]->{ProcessId},\$Info)
+;
            $self->{Info} = $Info;
            my @data = (
                $EnumInfo[$j]->{ProcessName},
                $Info->{PageFaultCount},
                $Info->{PeakWorkingSetSize},
                $Info->{WorkingSetSize},
                $Info->{QuotaPagedPoolUsage},
                $Info->{QuotaNonPagedPoolUsage},
                $Info->{PagefileUsage});
        }
    }

    return $self;
}

#----------------------------------------------------------
sub getProcessMemInfo {
    my $self = shift;
    $self->{obj}->GetProcessMemInfo($self->{EnumInfo}{ProcessId},\$sel
+f->{Info});
}

#----------------------------------------------------------
sub printProcessMemInfoShort {
    my $self = shift;
    $self->getProcessMemInfo;
    printf("\n\n%17.15s%15.14s%12.11s%12.11s\n\n",
            "[Name]","[PageFaults/s]", "[PeakWS]","[WS]")
            unless $self->{printed}++;
    printf("%17.15s%15.14s%12.11s%12.11s\n",
        $self->{EnumInfo}{ProcessName},
        $self->{Info}{PageFaultCount},
        $self->{Info}{PeakWorkingSetSize},
        $self->{Info}{WorkingSetSize});
}

1;

__END__
[download]

In this little exercice I can see just about every OO benefit that I listed above.
Convinced?

HTH
Rudif

In reply to Re: Hacking with objects by Rudif
in thread Hacking with objects by frankus

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