On Thu, 12 Mar 2020 at 23:55, Andrew Barnert <abarnert@yahoo.com.via.e4ward.com> wrote:
Because Julian’s patch has nothing to do with discarding the temporary references. It has to do with knowing that an array is safe to reuse.
Sorry, but I do not understand. Are you saying that the patch does not create a new temporary ndarray, but modifies in-place the old temporary ndarray? And that he knows that is temporary because refcount is 1? Anyway, I modified a little the Chris' code class Thing: def __init__(self, name): self.name = name print("Creating", self) def __repr__(self): return f"{self.__class__.__name__}({self.name})" def __add__(self, other): return self.__class__(self.name + other.name) def __del__(self): print("Deleting", self, " - ID:", id(self)) a = Thing("a") b = Thing("b") c = Thing("c") d = Thing("d") print("######## Before statement") z = a + b + c + d print("######## After statement") Result: Creating Thing(a) Creating Thing(b) Creating Thing(c) Creating Thing(d) ######## Before statement Creating Thing(ab) Creating Thing(abc) Deleting Thing(ab) - ID: 140185716001088 Creating Thing(abcd) Deleting Thing(abc) - ID: 140185715998976 ######## After statement Deleting Thing(a) - ID: 140185717096992 Deleting Thing(b) - ID: 140185717130192 Deleting Thing(c) - ID: 140185717176784 Deleting Thing(d) - ID: 140185715998880 Deleting Thing(abcd) - ID: 140185716001088 As you can see, Thing(abcd) has the same id of Thing(ab). So what Eric Wieser wanted is already implemented in Python, for temporary objects.