[Python-Dev] PEP 487 vs 422 (dynamic class decoration)

[Martin Teichmann]

Hi everyone,

for those new to the discussion, I am the author of PEP 487,
which has been discussed here:
https://mail.python.org/pipermail/python-ideas/2015-February/032249.html

> The concern is twofold: it breaks proper information hiding/DRY, *and*
> it fails silently.  It should not be necessary for clients of package
> A1 (that uses a decorator built using package B2) to mixin a metaclass
> or decorator from package C3 (because B2 implemented its decorators
> using C3), just for package A1's decorator to work properly in the
> *client package's class*.  (And then, of course, this all silently
> breaks if you forget, and the breakage might happen at the A1, B2, or
> C3 level.)

I am just not capable to understand things at such an abstract level,
would it be possible to give a simple example on what and how
you did things in python 2?

> IOW, there's no need to modify the core just to have *that* feature,
> since if you control the base class you can already do what PEP 487
> does in essentially every version of Python, ever.  If that's all PEP
> 487 is going to do, it should just be a PyPI package on a
> stdlib-inclusion track, not a change to core Python.  It's not
> actually adding back any of the dynamicness (dynamicity?
> hookability?) that PEP 3115 took away.

That was my point. You can find the PyPI package at:
https://pypi.python.org/pypi/metaclass

Greetings

Martin