I started off with short simple scripts to modify thousands of xml files. I would put some simple print statements in print "text,text,text\n";to log what was happening in each file in CSV format. The more I learned about XML::LibXML the more complex my scripts became and the more data points I wanted to log. I switched to print "$str1,$str2,$str3,$str4\n";. All the action was being done in a 'run_per_file' type sub. I ended up with a couple of hundred lines of code that is getting hard to keep track of in that sub. I wanted to break it up into smaller subs but the whole print statement problem was too much hassle. If something was found in an xml file that caused the need to skip to the next file I couldn't just use "return" since it would only return from that sub, not the 'run_per_file' subroutine. That means I needed to test the return value of the subs from within the 'run_per_file' subroutine.

So I have two problems here:

  • Logging CSV format without having to change a bunch of print statements to add a column. Also I need to reinitialize the column values each time the 'run_per_file' subroutine started.
  • Breaking up a large subroutine and still being able to print and skip to the next file from within a sub-sub.

    • I have looked at log4perl but by the time you format the string you pass it you have these same problems.

    I'm not thrilled with the approach below. I'm using the csv hash for program variables. I'm using the global constant in my subroutines. Is there some more straightforward or standard way to do this?

    #!/usr/bin/perl
use warnings;
use strict;

use constant CSV_COLUMNS => qw(
    file analog_id analog_cid epp_res_ck note
);
header();

#my @substation_files = glob( "*_subeditor.xml" );
my @substation_files = qw( test1.xml test2.xml );

if (@substation_files == 0) { die "No _subeditor.xml files found.\n" }

run_per_file($_) foreach @substation_files;

#**************************************************
#
#
sub run_per_file { 

    my ($xml_file) = @_;     
    
    my %csvdata;

    #my @vars = qw( file analog_id analog_cid epp_res_ck note);
    
    #$csvdata{$_} = '' foreach @vars;
    $csvdata{$_} = '' foreach (CSV_COLUMNS);
    
    $csvdata{file} = $xml_file;
    $csvdata{analog_cid} = "test.53.cb.stts";
    $csvdata{epp_res_ck} = find_epp(\%csvdata);
    
    return unless $csvdata{epp_res_ck} ne '';
    
    print_line(\%csvdata);
}

sub find_epp {
    my $hr = shift;
    
    if($hr->{file} eq "test1.xml") {
        return 'DEVTYPE=SW';
    }
    else {
        $hr->{note} .= ":error @ find_epp. ";
        print_line($hr);
        return '';
    }
}

sub print_line {

    my $hr = shift;

    #print "$hr->{file}, $hr->{analog_id}, $hr->{analog_cid}, $hr->{ep
+p_res_ck}, $hr->{note}\n";
    
    my $string = join ',', map {"$hr->{$_}"} ( CSV_COLUMNS );
    print $string, "\n";
}
 
#########################################################
# 
# subroutine to print header information, csv format.
#
sub header {
    my $timestamp=localtime;
    $timestamp =~ s/(.*) (\d{4})/$2 $1/; 

    print "report generated by $0\n";
    print "$timestamp\n";
    print "This program does something. \n\n";
    #print "Substation filename,analog_id,analog_cid,epp_res_ck, note\
+n";
    print join ',',( CSV_COLUMNS );
    print "\n";
}            

__DATA__
report generated by printsub.pl
2011 Wed Nov  9 10:16:50
This program does something. 

file,analog_id,analog_cid,epp_res_ck,note
test1.xml,,test.53.cb.stts,DEVTYPE=SW,
test2.xml,,test.53.cb.stts,,:error @ find_epp.

    [download]

    In reply to rfc: logging changes per file from subroutines by Lotus1

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