You can do ugly things to B even from within A

Yes - and my overloading of the arithmetic operations are done in XSubs - which leads to a fair bit of code clutter, but is procedurally clean and simple (IMO, at least).
I actually don't fully understand the code you've provided, but I'll certainly try to remedy that when I get the chance. (I'm not really a proper perl programmer.)

Having decided that Math::MPC's basic arithmetic operators should be capable of handling Math::MPFR objects (since the MPC library already provides functions that perform such arithmetic), it's a fairly simple exercise to insert the few required lines of code into the relevant Math::MPC XSubs.
If not for this "conundrum", that would be the end of the exercise.
Math::MPFR, which has no business to engage in arithmetic with Math::MPC objects, could be left as is - with no need to even mention this new capability in the Math::MPFR docs.

The solution I use is simple enough, but it involves making changes to the Math::MPFR overloading XSubs.

It's only a matter of inserting one line of code into a new if(condition){} block in each of those XSubs. And it just does a callback to (eg) Math::MPC::overload_minus(mpc_object, mpfr_object, &PL_sv_yes) with the assistance of a 20-line macro.
I'm happy enough with that, and I've used that technique without issue in a number of cross-class overloading situations - though I have no idea how expensive that solution is.
There's even no need to check whether Math::MPC has been loaded. If a Math::MPC object has been passed to a Math::MPFR function then we know that perl has loaded Math::MPC.
It's just a bit annoying that I have to go that extra step.
It would be much better if I could simply tell perl's overloading process "hey, in this case, use the overloading subroutine of the second object". But ... I can't do that :-((

Cheers,
Rob

In reply to Re^2: A little overloading conundrum by syphilis
in thread A little overloading conundrum by syphilis

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