4 ms·

Why not switch to making slots in classes the default and then making attribute changes to an object during runtime an opt-in? It will require a long grace

Why not switch to making __slots__ in classes the default and then making attribute changes to an object during runtime an opt-in? It will require a long grace period but wouldn't it help optimisation efforts immensely?

yedpodtrzitko 4y ago
That would mean all installed dependencies need to comply with this change as well, which is unlikely to happen in any realistic timeframe.
gjulianm 4y ago
That's going to require quite a lot of changes, it's a giant breaking change. All classes would need someone to go around finding all the attributes that are created and adding an __slots__ dictionary, to avoid regular attribute initialization in __init__ failing. It's a massive task, and it would completely break backwards compatibility for performance gains that not everybody will need.
BurningFrog 4y ago
Where can I read about what kind of performance improvements `__slots__` brings?
- WillDaSilva 4y ago
  The Python docs themselves is a good place to start: https://docs.python.org/3/reference/datamodel.html#slots https://docs.python.org/3/reference/datamodel.html#slots The Python wiki also has some good info about it: https://wiki.python.org/moin/UsingSlots https://wiki.python.org/moin/UsingSlots
- disconnect3d 4y ago
  Apart from the official docs, this video also explains the low level data layout (in CPython) that slots introduce: https://www.youtube.com/watch?v=Iwf17zsDAnY https://www.youtube.com/watch?v=Iwf17zsDAnY
anamax 4y ago
default __slots__ breaks a lot of monkey patching. An "easier" change would be to add a class attribute "no__dict__", which says that the __dict__ attribute can't be used, which lets the implementation do whatever it wants. That can be incrementally added to classes. Another option is a "no__getattr__" attribute, which disables gettattr and friends.

4 ms·

Why not switch to making slots in classes the default and then making attribute changes to an object during runtime an opt-in? It will require a long grace

by SuaveSteve 4y ago

yedpodtrzitko 4y ago
That would mean all installed dependencies need to comply with this change as well, which is unlikely to happen in any realistic timeframe.
gjulianm 4y ago
That's going to require quite a lot of changes, it's a giant breaking change. All classes would need someone to go around finding all the attributes that are created and adding an __slots__ dictionary, to avoid regular attribute initialization in __init__ failing. It's a massive task, and it would completely break backwards compatibility for performance gains that not everybody will need.
BurningFrog 4y ago
Where can I read about what kind of performance improvements `__slots__` brings?
- WillDaSilva 4y ago
  The Python docs themselves is a good place to start: https://docs.python.org/3/reference/datamodel.html#slots https://docs.python.org/3/reference/datamodel.html#slots The Python wiki also has some good info about it: https://wiki.python.org/moin/UsingSlots https://wiki.python.org/moin/UsingSlots
- disconnect3d 4y ago
  Apart from the official docs, this video also explains the low level data layout (in CPython) that slots introduce: https://www.youtube.com/watch?v=Iwf17zsDAnY https://www.youtube.com/watch?v=Iwf17zsDAnY
anamax 4y ago
default __slots__ breaks a lot of monkey patching. An "easier" change would be to add a class attribute "no__dict__", which says that the __dict__ attribute can't be used, which lets the implementation do whatever it wants. That can be incrementally added to classes. Another option is a "no__getattr__" attribute, which disables gettattr and friends.