Sign bug in Number::Format

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

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Re: Sign bug in Number::Format by toolic (Bishop) on Jun 05, 2012 at 20:23 UTC
The POD for Number::Format mentions a `format_negative` function. ~~I don't think `format_number` handles negative numbers, by design.~~ UPDATE: Nevermind... this prints a negative value: `print Number::Format::format_number(-0.0004,5)` [download]	[reply] [d/l] [select]
Re: Sign bug in Number::Format by herveus (Prior) on Jun 05, 2012 at 20:13 UTC
Howdy! What were you expecting to get? A quick glance at the module documentation suggests that the output is what should have come out. yours, Michael	[reply]
Re^2: Sign bug in Number::Format by ikegami (Patriarch) on Jun 05, 2012 at 20:15 UTC
He would expect a negative number. It does look like a bug.	[reply]
Re: Sign bug in Number::Format by Anonymous Monk on Jun 06, 2012 at 01:46 UTC
Apparently, it has now been reported as Bug #77643 for Number-Format: Non-negative result for negative argument	[reply]
Re: Sign bug in Number::Format (Devel::DumpTrace) by toolic (Bishop) on Jun 10, 2012 at 00:35 UTC
I believe Devel::DumpTrace quickly identifies the root cause of the problem. `perl -d:DumpTrace=+Number::Format -MNumber::Format -E 'say Number::For +mat::format_number(-0.00004, 5)' >>> -e:1:[__top__]: say Number::Format::format_number(-0.00004, 5 +) >>> Number/Format.pm:316:[_get_self]: unless (ref $_:(-4e-05,5)[0 +] && UNIVERSAL::isa($_:(-4e-05,5)[0], "Number::Format"))` [download] It seems that perl immediately interprets the value passed to the function (`-0.00004`) as scientific notation inside the function (`-4e-05`). A diff of this output vs. the output of a passing case with one less zero (`-0.0004`) shows where in the code the 2 cases diverge. I uploaded a patch to the open bug report. It then occurred to me to take a look a the coverage results (cpancover.com: new web site for CPAN code coverage). Sure enough, the line of code I patched was not covered by the test suite. This shows the value in using coverage to determine test quality. Read more... (729 Bytes) Morals of this story: Devel::DumpTrace is a handy debugging tool. Code coverage helps avoid bugs.	[reply] [d/l] [select]
Re: Sign bug in Number::Format by ww (Archbishop) on Jun 05, 2012 at 20:54 UTC
Bug? It looks correct to me: 4 x 10^-5 = 0.00004 and 0.00004 = 4 x 10^-5 or 4e-05 Ooops (ikegami & toolic bring me to my senses): DB<3> print Number::Format::format_number(-0.0004,5) -0.0004 Peripheral note: strikeout makes "=" look like -.	[reply]