Useless use of concatenation (.) or string in void context

[tobyink]

Migrated from rt.cpan.org #94259 (status was 'open')

Requestors:

• tomjudge@cisco.com

Attachments:

• patch-libJSONSchema__Helper.pm
• JSON-Schema-0.016-useless-use-in-void-context.patch

From tomjudge@cisco.com on 2014-03-27 21:13:59 :

Useless use of concatenation (.) or string in void context at /usr/local/lib/perl5/site_perl/5.16/JSON/Schema/Helper.pm line 311 (#1) (W void) You did something without a side effect in a context that does nothing with the return value, such as a statement that doesn't return a value from a block, or the left side of a scalar comma operator. Very often this points not to stupidity on your part, but a failure of Perl to parse your program the way you thought it would. For example, you'd get this if you mixed up your C precedence with Python precedence and said

    $one, $two = 1, 2;

when you meant to say

    ($one, $two) = (1, 2);

Another common error is to use ordinary parentheses to construct a list
reference when you should be using square or curly brackets, for
example, if you say

    $array = (1,2);

when you should have said

    $array = [1,2];

The square brackets explicitly turn a list value into a scalar value,
while parentheses do not.  So when a parenthesized list is evaluated in
a scalar context, the comma is treated like C's comma operator, which
throws away the left argument, which is not what you want.  See
perlref for more on this.

This warning will not be issued for numerical constants equal to 0 or 1
since they are often used in statements like

    1 while sub_with_side_effects();

String constants that would normally evaluate to 0 or 1 are warned
about.

Useless use of concatenation (.) or string in void context at /usr/local/lib/perl5/site_perl/5.16/JSON/Schema/Helper.pm line 316 (#1) Useless use of concatenation (.) or string in void context at /usr/local/lib/perl5/site_perl/5.16/JSON/Schema/Helper.pm line 339 (#1) Useless use of concatenation (.) or string in void context at /usr/local/lib/perl5/site_perl/5.16/JSON/Schema/Helper.pm line 344 (#1)

[tobyink]

From walker@cpan.org on 2014-05-21 20:03:05 :

Misplaced paren. Here's the patch.

[tobyink]

From kaoru@slackwise.net (@kaoru) on 2014-06-09 08:36:13 :

I can confirm that this patch fixes the problem and that JSON::Schema works with the fix in my Real World Use Case(tm)

Hope the patched version will be on its way to CPAN soon :-)

• Alex

[tobyink]

From ruz@cpan.org (@ruz) on 2015-06-01 22:22:25 :

Updated patch for 0.16. This bites me quite hard as some module I can not figure out which makes these warnings fatal :(

I'm willing to co-maint this module (PAUSE account RUZ) on the terms you announced in another module.

On Mon Jun 09 04:36:13 2014, KAORU wrote:

I can confirm that this patch fixes the problem and that JSON::Schema works with the fix in my Real World Use Case(tm)

Hope the patched version will be on its way to CPAN soon :-)

• Alex

-- Best regards, Ruslan.