Preferred bug tracker

Please visit the preferred bug tracker to report your issue.

This queue is for tickets about the Perl-Critic CPAN distribution.

Report information
The Basics
Id:
41633
Status:
rejected
Priority:
Low/Low
Queue:

People
Owner:
Nobody in particular
Requestors:
EDAVIS [...] cpan.org
Cc:
AdminCc:

BugTracker
Severity:
(no value)
Broken in:
1.092
Fixed in:
(no value)



Subject: Variables::RequireInitializationForLocalVars should not apply to $/
PBP says that when you use 'local' you should explicitly initialize the value. Hence the policy Variables::RequireInitializationForLocalVars. However, PBP (on page 213) explicitly recommends the following idiom: my $code = do { local $/; <$in> }; In a way this is an inconsistency in PBP. But I think the right way to resolve the contradiction is to be generous, and make RequireInitializationForLocalVars tolerate 'local $/'. (The 'local $/' idiom is also recommended in perlfaq5. So I think it is reasonable for it to be treated as a best practice and granted an exemption from the rule that you must always have assignment with 'local'.)
Subject: Re: [rt.cpan.org #41633] Variables::RequireInitializationForLocalVars should not apply to $/
Date: Thu, 11 Dec 2008 20:41:34 -0600
To: bug-Perl-Critic@rt.cpan.org
From: Elliot Shank <perl@galumph.com>
EDAVIS via RT wrote:
Show quoted text
> In a way this is an inconsistency in PBP. But I think the right way to > resolve the contradiction is to be generous, and make > RequireInitializationForLocalVars tolerate 'local $/'.
I disagree. Someone new to perl isn't going to understand the difference when they read your code.
On Thu Dec 11 12:32:19 2008, EDAVIS wrote:
Show quoted text
> So I think it is reasonable for it to be treated as a best practice > and granted an exemption from the rule that you must always have > assignment with 'local'.)
I also disagree, but for a different reason. Wherever possible, I believe that Conway attempts to present each guideline independently. That way, you can understand (and adopt) each guideline without necessarily having to understand (and adopt) other guidelines. The example you cited is in the context of using do{} blocks for file slurping, which is orthogonal to the issue of initializing localized variables. So from that perspective, I believe that the inconsistency is actually deliberate.
On Thu Dec 11 12:32:19 2008, EDAVIS wrote:
Show quoted text
> my $code = do { local $/; <$in> };
I prefer: use File::Slurp qw(read_file); my $content = read_file $filename; which is an order of magnitude more readable. read_file also works on filehandles, but that's somewhat less intuitive. Chris
Subject: Re: [rt.cpan.org #41633] Variables::RequireInitializationForLocalVars should not apply to $/
Date: Fri, 12 Dec 2008 20:45:44 -0600
To: bug-Perl-Critic@rt.cpan.org
From: Elliot Shank <perl@galumph.com>
Chris Dolan via RT wrote:
Show quoted text
> I prefer: > > use File::Slurp qw(read_file); > my $content = read_file $filename; > > which is an order of magnitude more readable. read_file also works on > filehandles, but that's somewhat less intuitive.
Not to mention that for large files it's a lot faster.
I was going to say that File::Slurp doesn't support reading from an existing filehandle, but I see that it does. (I just grepped the manual page for 'filehandle' and found no matches...) Anyway, it's strange that Conway in one part says that the undef-ing behaviour of 'local $x' should be avoided, while elsewhere deliberately relying on it (with a paragraph or two to explain how the 'local $/' idiom works). But if each recommendation is treated as independent, then it's correct for perlcritic to warn on all uses of 'local x', even if it means that recommended 'best practice' code from one part of PBP is then flagged as un-best practice according to a different part. I would suggest adding a new policy to prohibit setting $/ to undef at all (whether with 'local $/' or '$/ = undef') and suggest File::Slurp instead. If I had realized that File::Slurp supports filehandles, that's certainly what I would have used.


This service runs on Request Tracker, is sponsored by The Perl Foundation, and maintained by Best Practical Solutions.

Please report any issues with rt.cpan.org to rt-cpan-admin@bestpractical.com.