There's a pragma designed for constants. 'perldoc constant' for the manpage, but basically, it's like this:

use constant PIE => "Warm Apple";
print "pie: ", PIE, "\n";
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kelan

Perl6 Grammar Student

which is an attempt to create a CONSTANT which looks like variable

use vars qw( $PIE );
*PIE = \"Warm Apple";
print "pie: $PIE\n";
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You were pretty specific, so I'm assuming you were already aware of use constant PIE => "Warm Apple"; which results in a constant sub that can't be interpolated into strings (easily.)

-sauoq
"My two cents aren't worth a dime.";

they're not that difficult to interpolate:

use constant PIE => "Warm Apple";
print "The value of PIE is @{[ PIE ]}.\n";
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which gives:

The value of PIE is Warm Apple.

--
bowling trophy thieves, die!

The reference-dereference trick works even with scalars (which is clearer, IMHO: we're a printing a scalar, not a sui generis array):

print "The value of PIE is ${ \PIE }.\n";
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  sub CONST::TIESCALAR { bless \(my $v = pop), shift }
  sub CONST::FETCH { ${(shift)} }

  tie $x, CONST => 4;

  print "$x\n";
  $x = 7; # run-time error
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Thanks to kelan, perrin, sauoq, WBT, larsen, dpuu, and nite_man for the replies. You all were correct in assuming that I didn't want to use

  use constant PIE => "Warm Apple";
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I find

print "The value of PIE is ${ \PIE }.\n";
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or even

 print "pie: ", PIE, "\n";
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not pleasing to read or write. The former is truly ugly, and the later looks a bit like a filehandle.

Also, I have an existing code base with lots of scalar variables that are actually constants, so dpuu's solution is easiest to implement for me.

Cheers

--Fred

---

Nothing is too wonderful to be true
-- Michael Faraday

use strict;
use vars qw($PIE);
$PIE = 'Pumpkin';
print "pie: $PIE\n";
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You're talking about global variables, not constants.

He's talking about old-school constants... (you know... the way we used to do it... back in the paradise garage...)

$ perl -le '*PIE=\"Apple"; $PIE = "foo"'
Modification of a read-only value attempted at -e line 1.
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Please excuse my Doc Martin impression.

-sauoq
"My two cents aren't worth a dime.";

      
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SV* sv_bless(SV* sv, HV* stash);