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This queue is for tickets about the XML-XPath CPAN distribution.

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The Basics
Id: 30818
Status: resolved
Priority: 0/
Queue: XML-XPath

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Owner: MANWAR [...] cpan.org
Requestors: tokuhirom [...] gmail.com
Cc:
AdminCc:

Bug Information
Severity: Normal
Broken in: 1.21
Fixed in: 1.22



Subject: behaivior of division by zero
I want to change the behavior of division by zero, likes follow. Show quoted text
>>
including division by zero, has a well-defined result. In IEEE 754 arithmetic, a ÷ 0 is positive infinity when a is positive, negative infinity when a is negative, and NaN (not a number) when a = 0. http://en.wikipedia.org/wiki/Division_by_zero#Division_by_zero_in_computer_arithmetic << I think, XML::XPath cannot use valid substring() function by current op_div implementation. follow is a patch. === t/33op_div.t ================================================================== --- t/33op_div.t (revision 7247) +++ t/33op_div.t (local) @@ -0,0 +1,15 @@ +use strict; +use warnings; +use Test::More tests => 5; +use XML::XPath; + +my $xp = XML::XPath->new(ioref => *DATA); +ok($xp); + +is $xp->findvalue('4 div 2'), 2; +is $xp->findvalue('4 div 0'), 'Infinity'; +is $xp->findvalue('-4 div 0'), '-Infinity'; +is $xp->findvalue('0 div 0'), 'NaN'; + +__END__ +<p></p> === XPath/Expr.pm ================================================================== --- XPath/Expr.pm (revision 7247) +++ XPath/Expr.pm (local) @@ -508,18 +508,26 @@ my $lh_results = $lhs->evaluate($node); my $rh_results = $rhs->evaluate($node); + # handle zero devided cases. + if ($rh_results->to_number->value == 0) { + my $lv = $lh_results->to_number->value; + if ($lv == 0) { + return XML::XPath::Literal->new('NaN'); + } elsif ($lv > 0) { + return XML::XPath::Literal->new('Infinity'); + } elsif ($lv < 0) { + return XML::XPath::Literal->new('-Infinity'); + } else { + die "CAN'T REACH HERE"; + } + } + my $result = eval { $lh_results->to_number->value / $rh_results->to_number->value ; }; - if ($@) { - # assume divide by zero - # This is probably a terrible way to handle this! - # Ah well... who wants to live forever... - return XML::XPath::Literal->new('Infinity'); - } return XML::XPath::Number->new($result); }
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Hi, Thanks for raising the issue and patch as well. I will soon patch the code. Best Regards, Mohammad S Anwar
Resolved.


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