in reply to Re^14: Try::Tiny and -E
in thread Try::Tiny and -E

> False positive:

as I already said

> > In theory you could no feature "try" later in a sub-scope to re-enable those exports, but that's a very convoluted edge-case.

> > And I was mostly talking about "warning", warnings can be disabled if this convoluted edge-case is warranted.

Nobody does this accidentally or he/she is just dumb copy-pasting. Requiring to silence the warning with something like no warnings "masking" would be adequate. (there is no warnings category "masking" yet, but shadow exists, That's a matter of debate)

Anyway, do you have an example of a false positive which is less constructed?

FWIW: I provided an example for a false positive on reddit, if feature-try (Not Try::Tiny) is activated inside a class and was warning about name-clashes with method-names. This wouldn't make sense, because methods can't clash with built-ins.

But this is also kind of convoluted, methods are not imported and features are activated in the head lines of a scope/file, before methods are defined.

Cheers Rolf
(addicted to the Perl Programming Language :)
see Wikisyntax for the Monastery

Replies are listed 'Best First'.
Re^16: Try::Tiny and -E (False Positive)
by ikegami (Patriarch) on Jan 03, 2026 at 16:57 UTC

    Anyway, do you have an example of a false positive which is less constructed?

    You mean less simplified? I posted the minimal case: feature enabled for use Try::Tiny;, but not enabled at the call site. If you want to created an obfuscated example, I'll leave obfuscation to you.

[reply]
[d/l]
      > You mean less simplified?

      No I meant more plausible.

      Perl is so flexible that you can most likely create false positives for every warning.

      Doesn't mean they appear frequently enough for not being tolerable or solvable.

      Here a similar example where redefine is causing a "false positive"

      use strict;
use warnings;
use feature "say";
#no warnings 'redefine';
sub tst {1} 
BEGIN { $a = \&tst }
sub tst {2}
BEGIN { $b = \&tst }              
say &$a;
say &$b;

      [download]
      perl false_postive_redefine.pl
Subroutine tst redefined at false_postive_redefine.pl line 7.
1
2

      [download]

      And here a solution to your example.

      Just move the use Try::Tiny into the scope where it belongs. This makes the code also far clearer.

      use feature "try";
use constant CHECK_HINTHASH => 0;
sub check_hinthash {warn "feature_try = ".$^H{feature_try} if CHECK_HI
+NTHASH}
#...

BEGIN { check_hinthash() }    # feature enabled

{
  no feature qw( try );
  BEGIN { check_hinthash() }    # feature disabled
  use Try::Tiny qw( try catch );
   
  try { ... };   
}

BEGIN { check_hinthash() }    # feature enabled

# try { ... };  <-- would fail

      [download]

      Cheers Rolf
      (addicted to the Perl Programming Language :)
      see Wikisyntax for the Monastery

[reply]
[d/l]
[select]

        > You mean less simplified?

        No I meant more plausible.

        That just means obfuscated here, which I politely called less simplified.

[reply]

In Section Seekers of Perl Wisdom