A question about PERL versioning.

VincentK has asked for the wisdom of the Perl Monks concerning the following question:

Hello everyone. Long time reader, first time poster here.

On my Windows 7 box, when I run the following command , I see that I have PERL version 5.14 installed.

    perl -v
    
    This is perl 5, version 14, subversion 2 (v5.14.2) built for MSWin
+32-x64-multi-thread
    (with 1 registered patch, see perl -V for more detail)
    
    Copyright 1987-2011, Larry Wall
    
    Binary build 1402 [295342] provided by ActiveState http://www.Acti
+veState.com
    Built Oct  7 2011 15:19:36
[download]

However, when I run the following script without an explicit 'use 5.14;' notation, I receive an error.

    use strict;
    say "sent text via say";
[download]

This works

    use strict;
    use v5.14;
    say "sent text via say";
[download]

Within the script if I ask for the version , I receive back '5.014002'. This is not the same as v5.14.2, correct? Or is it?

    use strict;
    print $];
[download]

Am I to understand that by default version 5.014002 not 5.14 is being used?

I apologize if I am missing obvious here. Thank you very much.

Comment on A question about PERL versioning. Select or Download Code

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Re: A question about PERL versioning. by RichardK (Parson) on Oct 09, 2013 at 16:16 UTC
The help for say says this :- `This keyword is available only when the "say" feature is enabled, or when prefixed with "CORE::"; see feature. Alternately, include a "use v5.10" or later to the current scope.` [download]	[reply] [d/l]
Re: A question about PERL versioning. by ww (Archbishop) on Oct 09, 2013 at 16:16 UTC
The (non-issue) is that `say` is one of the (recent) features that remain optional in 5.14 (and in 5.16). If you want to use it, put `use 5.014;` in your header; if not, use `print`.	[reply] [d/l] [select]
Re: A question about PERL versioning. by VincentK (Beadle) on Oct 09, 2013 at 16:31 UTC
I think I understand now. My base version is '5.14', but if I need to use optional features of the version, I need to tell PERL to explicity use that version. I didn't realize that 'say' was an optional command. I don't really need to use 'say', I was just confused by the PERL interpreter reporting back that it didn't know what 'say' was without the explicit version call. Thank you so much to everyone for the replies and for your patience.	[reply]
Re^2: A question about PERL versioning. by Laurent_R (Canon) on Oct 09, 2013 at 16:50 UTC
The say feature was introduced in Perl version 5.10. In order not to break programs written under older versions which might for example use a say function for something else, the say features requires a use pragma such as use 5.10 or use 5.14. This way, older programs continue to work properly, but you can use say in new programs through the use pragma. As for versions, 5.14.2 and 5.014002 are just the same, two differents notations for the same version.	[reply]
Re^2: A question about PERL versioning. by Anonymous Monk on Oct 09, 2013 at 16:37 UTC
Some of us would be thankful to you if you would use "Perl" (note the case) to refer to the programming language, modules, and use "perl" to refer to the interpreter.	[reply]
Re^2: A question about PERL versioning. by Anonymous Monk on Oct 10, 2013 at 01:31 UTC
No problemo :) The changes are documented in perldeltas, (http://perldoc.perl.org/index-history.html) like perl5100delta#say() `$ perl -E " say sprintf q{v%vd %f }, $^V, $] " v5.16.1 5.016001` [download] Grab yourself a copy of the free book Modern Perl a loose description of how experienced and effective Perl 5 programmers work....You can learn this too. , it also explains this	[reply] [d/l]
Re: A question about PERL versioning. by 2teez (Vicar) on Oct 09, 2013 at 19:35 UTC
Hi VincentK Within the script if I ask for the version , I receive back '5.014002'. This is not the same as v5.14.2, correct? Or is it? `use strict; print $];` [download] You probably what to check the documentation on $OLD_PERL_VERSION $] and $PERL_VERSION $^V If you tell me, I'll forget. If you show me, I'll remember. if you involve me, I'll understand. --- Author unknown to me	[reply] [d/l]
Re: A question about PERL versioning. by Anonymous Monk on Oct 09, 2013 at 15:44 UTC
same difference.	[reply]
Re^2: A question about PERL versioning. by VincentK (Beadle) on Oct 09, 2013 at 15:49 UTC
I see. Then why do I need to use 'use v5.14' in order for the 'say' statement to work if the base system version is already '5.14'? Thanks.	[reply]
Re^3: A question about PERL versioning. by daxim (Curate) on Oct 09, 2013 at 16:16 UTC
required reading: feature, use `use version` implies a certain set of use feature. Specifically, use 5.010 and better enables feature say.	[reply]
Re^3: A question about PERL versioning. by Anonymous Monk on Oct 09, 2013 at 16:14 UTC
See "http://compgroups.net/comp.lang.perl.misc/why-can-t-i-use-say-with-version-5.14/2046730". I personally would prefer to have features already available without extra effort that are neither experimental nor introduced in current version. Then again this is Perl 5. `:-/`	[reply]
Re: A question about PERL versioning. by VincentK (Beadle) on Oct 10, 2013 at 14:24 UTC
Many thanks again for all of the feedback! I really appreciate it! I think I might just get a copy of "Modern Perl".	[reply]