use strict;
use warnings;
my %h = ('a'=>'123','b'=>'xxx','c'=>'');
my %newhash;                             
for(keys %h){ $newhash{$_} = $h{$_} if $h{$_} ne '' };
print join(",", keys %newhash)."\n";

##</code><code>##

use strict;
use warnings;

my %h = (
	'a' => 'aaa',
	'b' => ''
);

for(keys %h){
	next if $h{$_} eq '';
	my $evalstr = "\$$_ = '$h{$_}';";
	print "eval: $evalstr\n";
	eval $evalstr;
	die "eval $@" if $@;
}
print "a=$a\n";

##</code><code>##

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

my %params = (
    'default-0' => ['lakja', 'haljl', 'alka'],
    'default-1' => 'abc',
    'default-2' => [1, 54, 83, 23],
    'default-3' => [],
    'default-4' => '',
    'default-5' => '2019-06-26 00:00:10',    
);
my %cor = (
	'default-0' => '@arr_0',
	'default-1' => '$scal_1',
	'default-2' => '@arr_2',
	'default-3' => '@arr_3',
	'default-4' => '$scal_4',
	'default-5' => '$date_5',
	# etc
);
my $evalstr;

for(keys %params){
	my $varname = $cor{$_};
	die "var not found for $_" unless defined $varname;
	if( $varname =~ /^\$/ ){
		next if $params{$_} eq '';
		# quote value because it's a string: very basic rule of thumb...
		$evalstr = "$varname = '$params{$_}';";
	} elsif( $varname =~ /^@/ ){
		next if @{$params{$_}}==0;
		$evalstr = "$varname = ".'@{["'.join('","',@{$params{$_}}).'"]};';
	} else { die "can't handle $varname = ".$params{$_} }
	print "eval: $evalstr\n";
	eval $evalstr;
	die "eval $@" if $@;
}
print '@arr_0='."@arr_0\n".'$scal_1='."$scal_1\n";

##</code><code>##

Possible unintended interpolation of @arr_0 in string at b.pl line 45.
Name "main::arr_0" used only once: possible typo at b.pl line 45.
Name "main::scal_1" used only once: possible typo at b.pl line 45.
eval: @arr_0 = @{["lakja","haljl","alka"]};
eval: $date_5 = '2019-06-26 00:00:10';
eval: @arr_2 = @{["1","54","83","23"]};
eval: $scal_1 = 'abc';
@arr_0=lakja haljl alka
$scal_1=abc