note
kyle
<ol>
<li>For what other pairings of data types does <c>eq</c> ignore type?
<p>Basically every type. It forces each argument to a string before making a comparison.
</li>
<li>Is there a way to override this so that things belonging to different data types are always not equal?
<p>I'd probably write a custom comparison sub to do it.
<c>
use Scalar::Util qw( blessed reftype );
sub comparifier {
blessed $_[0] eq blessed $_[1]
&& reftype $_[0] eq reftype $_[1]
&& $_[0] eq $_[1]
}
</c>
<p>Along the same lines, you might be interested in [id://668351], whose subtext is "gosh, it's hard to figure out what a scalar really is."
</li>
<li>...how can I detect overloaded operators?
<p>Overloading applies to objects, not operators. (In Perl 6 you can override operators and/or write your own.) If you want to know if an object is overloading, use <c>overload::Overloaded( $obj )</c>. If you want to know if it's overloading <c>eq</c> in particular, you can check <c>overload::Method( $obj, 'eq' )</c>, but you'll also have to look for stringification (<c>overload::Method( $obj, q{""} )</c>).
</li>
<li>...how should I understand it?
<p>Just that <c>eq</c> forces its operands to be strings in order to do its job. A regular expression stringifies as you've found (it's a blessed reference to an [doc://undef] with regex magic added).
</li>
</ol>
<p>You might also be interested in <c>overload::StrVal( $obj )</c>, which gives you the string value of <c>$obj</c> without string overloading. For a regular expression, this is similar to "<c>Regexp=SCALAR(0x1d10860)</c>".
<p>I hope this helps.
<p><strong>Updated</strong> to fix a thinko in comparifier, thanks to [AnomalousMonk].
<p><strong>Updated</strong> again thanks to [jdporter].
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