Using 'no warnings' to disable own debug warn(ing)s?

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

According to warnings and perldiag it's possible to disable special warning classes in a lexical scope. (like the uninitialized one in the example)

Is it also possible to use this mechanism to disable my own debug messages for a scope?

(I'm aware about the possibility to manipulate $SIG{"__WARN__"} handler, but trying not to reinvent the wheel².)

use strict;
use warnings;
my $x;

{
    no warnings;
#    no warnings 'uninitialized';
    print "$x";
    warn "inside";
}
print "$x";
warn "outside";
[download]

inside at d:/Users/lanx/pm/no_warn.pl line 9.
Use of uninitialized value $x in string at d:/Users/lanx/pm/no_warn.pl
+ line 11.
outside at d:/Users/lanx/pm/no_warn.pl line 12.
[download]

Cheers Rolf
_{(addicted to the Perl Programming Language :)

Wikisyntax for the Monastery}

²) and overusing Pad::Walker

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Re: Using 'no warnings' to disable own debug warn(ing)s? by LanX (Saint) on Jun 22, 2018 at 18:05 UTC
haukex send my a `/msg` saying that he's traveling ATM and can't test, but suggests trying `warnings::warnif` . (see `warnings` for details) I suppose he means registering an own private warning classes, which sounds like a good idea, when using a custom wrapper function... update hmm ... no ... the wrapper would be in another scope ... Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery}	[reply] [d/l] [select]
Re^2: Using 'no warnings' to disable own debug warn(ing)s? by haukex (Archbishop) on Jun 22, 2018 at 19:06 UTC
Well, my thinking was that since I've used warnings::register in my modules and `warnings::warnif` to create custom warnings, and that function is sensitive to `FATAL` warnings, I thought it'd be sensitive to `no warnings` as well, since AFAIK warn just unconditionally warns (and AFAIK the only way to catch it is with %SIG). And it does indeed work, but unfortunately it seems that it only works across package boundaries, I'm not entirely sure yet why, but from a quick look at the source it seems to be because it uses (parts of) Carp under the hood, looking up the call stack. `use warnings; use strict; { package Foo; use warnings::register; sub bar { warnings::warnif("bar: $_[0]"); } } { no warnings; Foo::bar("inside"); } Foo::bar("outside"); use warnings::register; use Carp; { no warnings; warn "warn"; warnings::warn("warnings::warn"); carp "carp"; warnings::warnif("inside 2"); } warnings::warnif("outside 2"); __END__ bar: outside at w.pl line 17. warn at w.pl line 23. warnings::warn at w.pl line 24. carp at w.pl line 25.` [download] So at the moment my only two suggestions are to either go across package boundaries like I did in the above, or write your own debug function, which I tend to do. Just one example from here: `sub _debug { my ($self, $lvl, @out) = @_; return if $self->{debug}<$lvl \|\| !@out; print STDERR __PACKAGE__, " DEBUG: ", @out, "\n"; } # ... $self->_debug(2, ...);` [download]	[reply] [d/l] [select]

update