in reply to Re^4: How to capture the "isn't numeric" warning?
in thread How to capture the "isn't numeric" warning?

You could get it from an object that overloads numification (0+) or int, and the sub handling the overload warns.

One could argue that isNumber gives the better result in that situation.

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Re^6: How to capture the "isn't numeric" warning?
by syphilis (Archbishop) on Jun 17, 2019 at 03:24 UTC
    You could get it from an object that overloads numification (0+) or int

    Yes, that would do it.

    I did find a case where Scalar::Util::looks_like_number and the OP's isNumber return a different value for the same argument, but it had nothing to do with emission of warnings.

    For the arguments Math::MPFR->new(), Math::MPFR->new('nan') and Math::MPFR->new('inf'), Scalar::Util::looks_like_number will return FALSE, while isNumber will return TRUE.

    But this is probably the fault of Math::MPFR, which stringifies all values the same way as the mpfr library.
    And those 3 expressions therefore get stringified as "@NaN@", "@NaN@" and "@Inf@" (respectively).

    Math::MPFR probably should fix this by doing a s/@//g on the string prior to returning it. (And I'll attend to that.)

    I'll also mention that there's a perl API subroutine also named looks_like_number, but it doesn't look for any magic and therefore returns FALSE for most objects.
    Actually, I don't know of any cases where it will return TRUE for an object ... but I'm wary of asserting that such a case doesn't exist, or couldn't be constructed ...

    Cheers,
    Rob
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