Re^3: question regarding "Tie" in Perl

That's no excuse for implementing a constant using tie.

use strict;
use warnings;

Internals::SvREADONLY(my $answer = 42, 1);

print "This interpolates: $answer\n";
$answer++;  # dies
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use Moops; class Cow :rw { has name => (default => 'Ermintrude') }; say Cow->new->name

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Re^4: question regarding "Tie" in Perl by BrowserUk (Patriarch) on Nov 05, 2013 at 01:49 UTC
Cool'n'all as that is, by deferring the construction of constants to runtime, you disavail yourself of various compile-time optimisations that Perl has. Even the very act of interpolating a read-only variable is an active pessimisation, as whilst perl will enforce the read-onliness, Perl does not (cannot) know that it need not re-interpolate the variable every time it is used: use constant CONSTANT => 10;; Internals::SvREADONLY( my $READONLY = 10, 1);; [Type of arg 1 to Internals::SvREADONLY must be one of [$%@] (not scal +ar assignment) at (eval 11) line 1, near "1)" $READONLY = 10; Internals::SvREADONLY( $READONLY, 1);; ++$READONLY;; [Modification of a read-only value attempted at (eval 13) line 1, <STD +IN> line 6. cmpthese -1,{ a=>q[ for(1..1000){ my $string = "the constant is " . CONSTANT . " +\n" } ], b=>q[ for(1..1000){ my $string = "the readonly is $READONLY\n"; } + ], };; Rate b a b 3893/s -- -46% a 7236/s 86% -- [download] A small a difference as that may be; it is all those avoidable small bits that add up. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l]

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Re^4: question regarding "Tie" in Perl
by BrowserUk (Patriarch) on Nov 05, 2013 at 01:49 UTC

Cool'n'all as that is, by deferring the construction of constants to runtime, you disavail yourself of various compile-time optimisations that Perl has.

Even the very act of interpolating a read-only variable is an active pessimisation, as whilst perl will enforce the read-onliness, Perl does not (cannot) know that it need not re-interpolate the variable every time it is used:

use constant CONSTANT => 10;;

Internals::SvREADONLY( my $READONLY = 10, 1);;
[Type of arg 1 to Internals::SvREADONLY must be one of [$%@] (not scal
+ar assignment) at (eval 11) line 1, near "1)"

$READONLY = 10; Internals::SvREADONLY( $READONLY, 1);;
++$READONLY;;
[Modification of a read-only value attempted at (eval 13) line 1, <STD
+IN> line 6.

cmpthese -1,{ 
    a=>q[ for(1..1000){ my $string = "the constant is " . CONSTANT . "
+\n" }  ],
    b=>q[ for(1..1000){ my $string = "the readonly is $READONLY\n"; } 
+       ],
};;
    Rate    b    a
b 3893/s   -- -46%
a 7236/s  86%   --
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A small a difference as that may be; it is all those avoidable small bits that add up.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

[reply]
[d/l]