How can I combine these regular expressions?

Question

Four very identical regular expressions. I am replacing the strings with the following scalar values. How can this be more efficient?

$line =~ s/\[(receiver)\]/$receiver/g;
$line =~ s/\[(place)\]/$place/g;
$line =~ s/\[(position)\]/$position/g;
$line =~ s/\[(company)\]/$company/g;

Thank you.

Answer 1

Consider just using a real templating system. Template Toolkit for instance is very easy.

Leaving that aside, you say you want it more efficient. Is its current perceived inefficiency a problem? If not, leave it alone.

You could do it all in one pass:

my %subst = (
    'receiver' => $receiver,
    'place'    => $place, 
    'position' => $position,
    'company'  => $company,
);
$line =~ s/\[(receiver|place|position|company)\]/$subst{$1}/g;

but this will act differently if, for instance, $receiver is 'place'.

Answer 2

Ok, let's see, what you want:

if you want to 'evaluate' the value of variable, that name you found in the string, then, you need:

my $receiver = 'rcv';
my $place = 'plc';
my $position = 'pstn';
my $company = 'cmpn';
my $allVariableNames = join('|',qw(receiver place position company));
$line = '[receiver]';
$line =~ s/\[($allVariableNames)\]/'$'.$1/eg;
#$line =~ s/\[($allVariableNames)\]/eval('$'.$1)/eg; <- smarter and shorter variant
print $line,"\n"; #contain $receiver
print eval($line), "\n";   # evaluate ($receiver) => get rcv

it is another way to do this task, see ysth' answer above