GSP
Quick Navigator

Search Site

Unix VPS
A - Starter
B - Basic
C - Preferred
D - Commercial
MPS - Dedicated
Previous VPSs
* Sign Up! *

Support
Contact Us
Online Help
Handbooks
Domain Status
Man Pages

FAQ
Virtual Servers
Pricing
Billing
Technical

Network
Facilities
Connectivity
Topology Map

Miscellaneous
Server Agreement
Year 2038
Credits
 

USA Flag

 

 

Man Pages


Manual Reference Pages  -  CONST::FAST (3)

.ds Aq ’

NAME

Const::Fast - Facility for creating read-only scalars, arrays, and hashes

CONTENTS

VERSION

version 0.014

SYNOPSIS



 use Const::Fast;

 const my $foo => a scalar value;
 const my @bar => qw/a list value/;
 const my %buz => (a => hash, of => something);



SUBROUTINES/METHODS

const CW$var, CW$value

const CW@var, CW@value...

const CW%var, CW%value...

This the only function of this module and it is exported by default. It takes a scalar, array or hash lvalue as first argument, and a list of one or more values depending on the type of the first argument as the value for the variable. It will set the variable to that value and subsequently make it readonly. Arrays and hashes will be made deeply readonly.

Exporting is done using Sub::Exporter::Progressive. You may need to depend on Sub::Exporter explicitly if you need the latter’s flexibility.

RATIONALE

This module was written because I stumbled on some serious issues of Readonly that aren’t easily fixable without breaking backwards compatibility in subtle ways. In particular Readonly’s use of ties is a source of subtle bugs and bad performance. Instead, this module uses the builtin readonly feature of perl, making access to the variables just as fast as any normal variable without the weird side-effects of ties. Readonly can do the same for scalars when Readonly::XS is installed, but chooses not to do so in the most common case. This may change in the future if someone takes up maintenance of Readonly, and the two modules may be convergence if that happens.

CAVEATS

Perl doesn’t distinguish between restricted hashes and readonly hashes. This means that:



 use Const::Fast;
 const my %a => (foo => 1, bar => 2);
 say 1 unless $a{baz}



Will give the error Attempt to access disallowed key ’baz’ in a restricted hash. You have to use exists $a{baz} instead. This is a limitation of perl that can hopefully be solved in the future.

ACKNOWLEDGEMENTS

The interface for this module was inspired by Eric Roode’s Readonly. The implementation is inspired by doing everything the opposite way Readonly does it.

AUTHOR

Leon Timmermans <fawaka@gmail.com>

COPYRIGHT AND LICENSE

This software is copyright (c) 2010 by Leon Timmermans.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

Search for    or go to Top of page |  Section 3 |  Main Index


perl v5.20.3 CONST::FAST (3) 2013-05-28

Powered by GSP Visit the GSP FreeBSD Man Page Interface.
Output converted with manServer 1.07.