Re^2: Incrementing "Infinity" bug

Hi Ken!

> As you were probably aware, warnings alert you and strictures disallow it altogether:

Yes, I became aware after posting the first time.

I expected inf and it's brothers˛ to be constants because of their magic behavior when being numified.

Introducing constantsš for inf, -inf and NaN (even all uppercase like INF) would help clarifying the situation.

Cheers Rolf

( addicted to the Perl Programming Language)

š) like I demonstrated here

˛) every string starting with inf (no matter if upper or lower case) numifies to inf:

  DB<106> $a="Infinity"+0
 => "inf"

  DB<109> $a="Inftyddssssd"+0
 => "inf"

  DB<110> $a="Inf"+0
 => "inf"

  DB<111> $a="InF"+0
 => "inf"
[download]

UPDATE: line 109 with"Inftyddssssd" fails with activated warnings, anything else with lc($else) ~~ ['inf','infinity'] won't

  DB<123> use warnings; $a='InFiNiTy'+0
 => "inf" 

 DB<125> use warnings;$a="Inftyddssssd"+0
Argument "Inftyddssssd" isn't numeric in addition (+) at (eval 74)[mul
+ti_perl5db.pl:644] line 2.
[download]

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Re^3: Incrementing "Infinity" bug by kcott (Archbishop) on Mar 25, 2013 at 16:28 UTC
I came across `Inf` (and friends) some years ago, decided they all looked somewhat flakey, and haven't used them since. Your posting has (somewhat) piqued my interest again. Here's some interesting results from Scalar::Util's `looks_like_number()` function. $ perl -E ' use Scalar::Util qw{looks_like_number}; my @infs = (inf, Inf, INF, infinity, Infinity, INFINITY, -inf, -Inf, -INF, -infinity, -Infinity, -INFINITY, Inftyddssssd, infighting, Infighting, -Inftyddssssd, -infighting, -Infighting); say "$_ : ", looks_like_number($_) for @infs; ' inf : 20 Inf : 20 INF : 20 infinity : 20 Infinity : 20 INFINITY : 20 -inf : 28 -inf : 28 -inf : 28 -inf : 28 -inf : 28 -inf : 28 Inftyddssssd : 0 infighting : 0 Infighting : 0 -Inftyddssssd : 0 -infighting : 0 -Infighting : 0 [download] I also noted that the documentation for this function links to perlapi - looks_like_number, which may be of interest ot you. -- Ken	[reply] [d/l] [select]
Re^4: Incrementing "Infinity" bug by LanX (Saint) on Mar 25, 2013 at 16:49 UTC
I suppose these numbers reflect some flags? something like: 2^3 for negative 2^2 for special value 2^4 for infinity couldn't find explanation in the docs. > decided they all looked somewhat flakey, agreed, but shouldn't we try to fix it. Don't you think the algorithm I used is a valid use case? (non-reachable integer) Cheers Rolf ( addicted to the Perl Programming Language)	[reply]