Exporter::require_version almost never gets called. See (tye)Re: Overriding Exporter::import.

I found it funny (and a little sad) that perldata.pod defines this new type of literal but avoids giving it a name. The 5.6.0 pods don't ever mention "v-string" but do eventually refer to these as "vectors of (ordinals|integers)".

As best as I can tell, there is absolutely no way to distinguish v53.46.52 from "5.4" once perl has parsed it. You could cheat a little and assume that if the version scalar already has a numeric value cached inside of it, then it probably isn't a ordinal vector.

You can use Devel::Peek to determine this or use the old hack:

    my $version= shift;
    if(  "0" eq ( $version ^ $version )  ) {
        # $version already has a numeric value
    } else {
        # $version is _only_ a string
    }
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Checking the code in universal.c, I see that the default method does something similar:

    if (!SvNIOK(sv) && SvPOK(sv)) {
        # ...
    }
    /* if we get here, we're looking for a numeric comparison,
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        - tye (but my friends call me "Tye")