Re: How can I suppress 'uninitialized' warnings in a CPAN module?

in reply to How can I suppress 'uninitialized' warnings in a CPAN module?

Thank you everyone for your comments!

I suppose the easiest solution would be to edit Tokenizer.pm, but part of me thinks that is a Bad Thing! ;)

I tried LanX's generic solution and it seems to work very well:

use warnings;
use strict;


p();
print "Test 1\n\n";
print undef;               # "Use of uninitialized value in print at .
+.."
print 'a'+1;               # "Argument "a" isn't numeric in addition (
++) at ..."
foo(1);
p();


{
    local $SIG{__WARN__} = \&suppress_UV_warning;    # <-------- Is th
+is correct ?

    p();
    print "Test 2\n\n";
    print undef;           # SUPPRESSED! "Use of uninitialized value i
+n print at ..."
    print 'a'+1;           # "Argument "a" isn't numeric in addition (
++) at ..."
    foo(2);
    p();
}


p();
print "Test 3\n\n";
print undef;               # "Use of uninitialized value in print at .
+.."
print 'a'+1;               # "Argument "a" isn't numeric in addition (
++) at ..."
foo(3);
p();


# generate some more warnings to check they are suppressed here too
sub foo
{
    my ($x) = @_;
    print "\n\n";
    print undef;           # SUPPRESSED IN TEST 2! "Use of uninitializ
+ed value in print at ..."
    print "foo $x" + 1;    # "Argument "foo n" isn't numeric in additi
+on (+) at ..."
}


# suppress "Use of uninitialized value" warnings only
sub suppress_UV_warning
{
    my ($message) = @_;

    if ($message =~ /^Use of uninitialized value/) { return; }

    warn $message;         # <-------- Is this correct ?
}


# print separating line
sub p
{
    print "\n", '-'x100, "\n";
}
[download]

Produces this output:

----------------------------------------------------------------------
+------------------------------
Test 1

Use of uninitialized value in print at D:\test\test.pl line 7.
Argument "a" isn't numeric in addition (+) at D:\test\test.pl line 8.
1

Use of uninitialized value in print at D:\test\test.pl line 38.
Argument "foo 1" isn't numeric in addition (+) at D:\test\test.pl line
+ 39.
1
----------------------------------------------------------------------
+------------------------------

----------------------------------------------------------------------
+------------------------------
Test 2

Argument "a" isn't numeric in addition (+) at D:\test\test.pl line 19.
1

Argument "foo 2" isn't numeric in addition (+) at D:\test\test.pl line
+ 39.
1
----------------------------------------------------------------------
+------------------------------

----------------------------------------------------------------------
+------------------------------
Test 3

Use of uninitialized value in print at D:\test\test.pl line 27.
Argument "a" isn't numeric in addition (+) at D:\test\test.pl line 28.
1

Use of uninitialized value in print at D:\test\test.pl line 38.
Argument "foo 3" isn't numeric in addition (+) at D:\test\test.pl line
+ 39.
1
----------------------------------------------------------------------
+------------------------------
[download]

I have 2 questions, are these 2 lines correct?
line 14 : local $SIG{__WARN__} = \&suppress_UV_warning;
line 50 : warn $message;

Comment on Re: How can I suppress 'uninitialized' warnings in a CPAN module? Select or Download Code

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Re^2: How can I suppress 'uninitialized' warnings in a CPAN module? by LanX (Saint) on Nov 17, 2013 at 23:04 UTC
> I have 2 questions, are these 2 lines correct? Correct yes but... > line 14 : local $SIG{__WARN__} = \&suppress_UV_warning; Personally I prefer anonymous subs if I never need to call them by name. > line 50 : warn $message; You should check the Perl-version, IIRC this causes an endless loop in Perl older < 5.8 (?) (Too lazy to look up when it was exactly fixed) Newer versions are fool proof. ;-) update Talking about "generic solutions": Please be aware that this approach doesn't help if the module in question is also recklessly overwriting `$SIG{__WARN__}` Therefore a safe way of overriding is to create a wrapper, which calls the overridden handler from within (if present in `$SIG{__WARN__}`). But you can only be sure after checking the source code of the module in question. Cheers Rolf ( addicted to the Perl Programming Language)	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re^2: How can I suppress 'uninitialized' warnings in a CPAN module?
by LanX (Saint) on Nov 17, 2013 at 23:04 UTC

> I have 2 questions, are these 2 lines correct?

Correct yes but...

> line 14 : local $SIG{__WARN__} = \&suppress_UV_warning;

Personally I prefer anonymous subs if I never need to call them by name.

> line 50 : warn $message;

You should check the Perl-version, IIRC this causes an endless loop in Perl older < 5.8 (?) (Too lazy to look up when it was exactly fixed)

Newer versions are fool proof. ;-)

update

Talking about "generic solutions":

Please be aware that this approach doesn't help if the module in question is also recklessly overwriting $SIG{__WARN__}

Therefore a safe way of overriding is to create a wrapper, which calls the overridden handler from within (if present in $SIG{__WARN__}).

But you can only be sure after checking the source code of the module in question.

Cheers Rolf

( addicted to the Perl Programming Language)

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