What if we separate the use cases. Here's what I mean:
1) When you write an anonymous function it is clear which function is meant. No problem. That's the function you always get.
2) When you write @func and func is a function inside the file--that is the function you get always. Isn't that what you meant by putting in the same file?
3) When you write @func and the function is not defined in the same file you get full function search including dynamic typing. This occurs at the time of use not creation.
I think this would behave the way I expect in every case my feeble mind has been able to imagine. Unless someone plays games with temporarily toggling the path back and fourth. So except for those (what I consider fringe and pathologic) cases octave would do what you expect it to 99.9% of the time?
IANAL, but I don't think this approach can infringe because a list of functions and pointers to whatever is never ever created and stored with the handle at the time of creation.
Am I missing something about how handles are expected to work?