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Using Hash element as variable

 

Using Hash element as variable
Sun751

1 Jul, 2009 - 12:50 AM
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To get rid of variables I am trying to use hash elements as following,

CODE

use strict;
use warnings;

my $config_file = 'release_config.ini';
my %config;

initilize_config(\%config,$config_file);
release_web(\%config);

sub initilize_config
{
    my ($HR_config,$file) = @_;
    open (my $fr, '<', "$file") || die "Unable to open configuration file: $file $!";
    while (my $line = <$fr>)
    {
        $line =~ tr/\r\n//d;
        next unless $line;
        if ($line =~ /=/)
        {
            my ($key,$val)=$line=~ /^(.*?)=(.*?)$/;
            $$HR_config{$key} = $val;
        }
    }
}

sub release_web
{
    my $HR_config = shift;
    change_dir($HR_config->{Distribution});
}

sub change_dir
{
    my $dir = shift;
    chdir($dir)|| die "chdir failed: Unable to change to directory, $dir $!\n";
}


Can any one suggest me if its smart way of write program or not ? Any suggestion please!!!

Cheers

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KevinADC

RE: Using Hash Element As Variable

1 Jul, 2009 - 10:20 AM
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Only going by the code I see, I would probably code it more like this:

CODE

use strict;
use warnings;

my $config_file = 'release_config.ini';
my $HR_config = initilize_config($config_file);
release_web($HR_config->{Distribution});

sub initilize_config {
    my ($file) = @_;
    my %temp;
    open (my $fr, '<', $file) || die "Unable to open configuration file: $file $!";
    while (my $line = <$fr>) {
         if ($line=~ /^(.*?)=(.*?)$/) {
           $temp{$1} = $2;
        }
    }
    return(\%temp);
}

sub release_web {
    my ($dir) = @_;
    chdir($dir)|| die "chdir failed: Unable to change to directory, $dir $!\n";;
}


The regexp might be better written like so:

CODE
if ($line=~ /^(.+?)=(.+?)$/) {


otherwise it could return undefined values for $1 and $2 since .*? can match nothing




This post has been edited by KevinADC: 1 Jul, 2009 - 10:22 AM
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dsherohman

RE: Using Hash Element As Variable

2 Jul, 2009 - 02:32 AM
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QUOTE(KevinADC @ 1 Jul, 2009 - 06:20 PM) *

The regexp might be better written like so:

CODE
if ($line=~ /^(.+?)=(.+?)$/) {


otherwise it could return undefined values for $1 and $2 since .*? can match nothing


Better still:
CODE
if ($line=~ /^([^=]+)=(.*)$/) {

For the first match, if you only want non-= characters, then ask for "only non-= characters", not "the shortest possible sequence of characters which is followed by an =". Aside from being more explicit about what you want, using the negated character class also completely eliminates any possibility that the regex engine could get confused on certain input strings and start backtracking in search of a better match.

For the second match, there's no point in making a match-to-end-of-line non-greedy. It can't match without consuming everything anyhow.

(Perhaps I should add "campaigner against abuse of non-greedy . in regex" to my forum signature... Or maybe "Knight of the Negated Character Class" sounds better...)
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KevinADC

RE: Using Hash Element As Variable

2 Jul, 2009 - 10:49 AM
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QUOTE(dsherohman @ 2 Jul, 2009 - 02:32 AM) *



Better still:
CODE
if ($line=~ /^([^=]+)=(.*)$/) {





I totally agree. I was just trying to stick with his code as much as I was comfortable with. But I would also write it like you suggest using a negated character class.
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