Re: Exploiting Perls idea of what is a number

If you approach the equivalence from the other direction, it becomes easier:

Two strings are equal iff

... they are equal as characters
or ... they are equal as numbers

When described that way, the expression becomes:

$a eq $b || $a == $b
[download]

This has the small drawback of equating undef and the empty string with 0 as well though.

Update It also has the other small drawback of considering all strings to be equal, which is a bit suboptimal...

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Re^2: Exploiting Perls idea of what is a number (oops) by tye (Sage) on Jul 08, 2008 at 12:57 UTC
That has the large drawback of declaring that `"foo"` is the same as `"cheesecake"` (while emitting two warnings). :) - tye	[reply]
Re^3: Exploiting Perls idea of what is a number (oops) by jettero (Monsignor) on Jul 08, 2008 at 13:12 UTC
Maybe `!($a cmp $b \|\| $a <=> $b)` would work... nope. -Paul	[reply] [d/l]
Re^3: Exploiting Perls idea of what is a number (oops) by rovf (Priest) on Jul 08, 2008 at 14:50 UTC
That has the large drawback of declaring that "foo" is the same as "cheesecake" (while emitting two warnings). :) In my particular application, a foo is indeed the same than a cheesecake! -- Ronald Fischer <ynnor@mm.st>	[reply]
Re^4: Exploiting Perls idea of what is a number (oops) by tye (Sage) on Jul 08, 2008 at 15:22 UTC
Then use `$a == $b`. The `$a eq $b \|\|` is just obfuscation. The only thing it changes is that it prevents warnings when given two equal, non-numeric strings (because if `$a eq $b`, then it will also be true that `$a == $b`). - tye	[reply] [d/l] [select]
Re^4: Exploiting Perls idea of what is a number (oops) by ikegami (Patriarch) on Jul 09, 2008 at 04:15 UTC
Then all you need is `my $result = do { no warnings 'numeric'; $x == $y };` [download]	[reply] [d/l]
Re^5: Exploiting Perls idea of what is a number (oops) by rovf (Priest) on Jul 09, 2008 at 06:49 UTC
Re^2: Exploiting Perls idea of what is a number by rovf (Priest) on Jul 08, 2008 at 13:11 UTC
`$a eq $b \|\| $a == $b` [download] I think I was too early with my response. Your suggestion, as elegant as it looks, would fail if $a and $b are unequal strings. In this case `$a eq $b` would result false, and `$a == $b` would be evaluated, yielding an error message because the arguments are not numeric... -- Ronald Fischer <ynnor@mm.st>	[reply] [d/l] [select]
Re^2: Exploiting Perls idea of what is a number by rovf (Priest) on Jul 08, 2008 at 12:56 UTC
Thank's a lot for the suggestions!! I think for my original problem I find your solution most convenient, but actually there is another part of the program where I now can replace my cumbersome regexp to test for numerics, by moritz's idea of using `Scalar::Util`. -- Ronald Fischer <ynnor@mm.st>	[reply] [d/l]