Concat正则表达式与常量声明中的字符串作为oneliner

Question

I am trying to declare a constant as an one liner like this:

use constant HOME_SCRIPT => "/home/george/". $0 =~ /(.*)\\.pl/;
The problem is that this returns: /home/george/1 . Ie it concats the number of matches of regex.
I tried:
use constant HOME_SCRIPT => ("/home/george/"). $0 =~ /(.*)\\.pl/;
use constant HOME_SCRIPT => "/home/george/". ($0 =~ /(.*)\\.pl/);
but same result.
Is it possible to create an oneliner for this?

Answer 1

use constant HOME_SCRIPT => "/home/george/". ($0 =~ /(.*)\.pl/)[0];

要么

use constant HOME_SCRIPT => join "", "/home/george/", $0 =~ /(.*)\.pl/;

Answer 2

If you are running Perl 5 version 14 or later, you can use non-destructive substitution via the /r modifier. Like this

use constant HOME_SCRIPT => ("/home/george/$0") =~ s/\.pl\z//r;

Or if you are forced to use something earlier, or would simply prefer a different method, you can write

use constant HOME_SCRIPT => '/home/george/' . ($0 =~ /(.*)\./, $1);