darn, constants are not interpolated in strings or regexes.

As I understand it, even with use constant, a constant in Perl is an in line sub. IE:

use constant PI    => 4 * atan2(1, 1);
[download]

is the short hand for

sub PI
{
    4 * atan2(1, 1);
}
[download]

Which, after compile time constant expression evaluation, simplifies to:

sub PI
{
    3.1415926536; # to the precision available on the machine running 
+the program
}
[download]

which the compiler can then in line where it would otherwise put a sub call.

> where it would otherwise put a sub call.

which isn't trivial within strings/regexes.

the "@{[...]}" trick works but is IMHO a bit oversized for this task.

  DB<109> use constant STR => 1..3

  DB<110> qr/[@{[ STR ]}]/
 => qr/[1 2 3]/
[download]

thats not interpolation anymore but inline eval.

Cheers Rolf

( addicted to the Perl Programming Language)

Here's another way, but I can't say it's any less klutzy. There seems to be no way to avoid the use of some kind of operator for disambiguation.

use warnings;
use strict;

use constant STR   => 'a string';
use constant STREF => \'ref to a string';

print qq{one way '${ \STR }' and another '${ +STREF   }' \n};
print qq{and with another disambiguation '${  STREF() }' \n};
[download]

Output:

c:\@Work\Perl\monks>perl constant_interpolation_1.pl
one way 'a string' and another 'ref to a string'
and with another disambiguation 'ref to a string'
[download]