Thanks a lot, Armin. If we go this way, it's easy to special case PyPy. On Mon, Jan 29, 2018 at 2:42 PM Armin Rigo wrote:

Hi,

On 29 January 2018 at 11:22, Tin Tvrtković wrote:

...

It's just that doing it this way is unconventional and a little scary. Would we be violating a Python rule somewhere and making stuff blow up later if we went this way?

No, it's semantically fine. But it comes with a heavy penalty on PyPy. I guess you don't see it because you measured something tiny, like creating the instance and then throwing it away---the JIT optimizes that to nothing at all in both cases. Not only is the creation time larger, but attribute access is slower, and the memory usage is larger.

A bientôt,

Armin.

Hi, On 30 January 2018 at 13:13, Antonio Cuni wrote:

sidenote: if you do the following, you can replace the __dict__ without incurring into performance penalties (Armin, please correct me if I'm wrong):

import __pypy__ def __init__(self): self.__dict__ = __pypy__.newdict('instance')

This is a no-op, which takes time to execute but indeed doesn't seem to disable the optimization. However I don't see the point. You may as well write it like that: def __init__(self, x, y, z): d = self.__dict__ d['x'] = x d['y'] = y d['z'] = z It is a bit slower than "self.x = x; self.y = y; self.z = z" in PyPy but doesn't throw away the optimization. On CPython it is probably faster. Armin