Hi,

I'm seeking perl wisdom against my "OO wisdom" ;-)
But maybe my OO wisdom needs to be updated, too.

I've written an XS speedup for Params::Util - and the author detects that my XS implementation of _INSTANCE differs to his perl implementation: The perl implementation simply calls $obj->isa($class) - and returns the result. The XS implementation checks first sv_derived_from and only in a negative result, it calls $obj->isa($class) (I think, I should even prove string equality of sv_reftype - but this is another story). My reason to implement it this way was: 

class A { ... };
class B : public A { ... };

[download]
B is a A

So what do you think? Should the XS implementation give the (overridable) isa method the precedence? Or is it just a limitation? Should the perl implementation better use UNIVERSAL::isa before trying the overridden method?

In reply to sv_derived_from vs. sub ISA by rehsack

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