Hi Gabriele,
On 01/04/2022 4:50 pm, Gabriele wrote:
Does this mean that this line in the bytecode library is likely to fail with
3.11, with no way to fix it?
You can pass the exception table the same way you pass all the other arguments.
The exception table depends on the code, but that is nothing new. The bytecode
library already recomputes the consts, names, etc.
TBH, calling `types.CodeType` didn't work for earlier versions either.
It just sort of worked, some of the time.
Cheers,
Mark.
https://github.com/MatthieuDartiailh/bytecode/blob/7b0423234b0e999b45a4eb0c58115b284314f46b/bytecode/concrete.py#L398
<https://github.com/MatthieuDartiailh/bytecode/blob/7b0423234b0e999b45a4eb0c58115b284314f46b/bytecode/concrete.py#L398>
On Fri, 1 Apr 2022, 10:40 Victor Stinner, <vstin...@python.org
<mailto:vstin...@python.org>> wrote:
I created https://bugs.python.org/issue47185
<https://bugs.python.org/issue47185> to discuss this issue:
either recompute automatically co_exceptiontable, or at least document
the change.
Victor
On Fri, Apr 1, 2022 at 11:21 AM Victor Stinner <vstin...@python.org
<mailto:vstin...@python.org>> wrote:
>
> ("Re: C API: Move PEP 523 "Adding a frame evaluation API to CPython"
> private C API to the internal C API")
>
> On Fri, Apr 1, 2022 at 11:01 AM Chris Angelico <ros...@gmail.com
<mailto:ros...@gmail.com>> wrote:
> >
> > On Fri, 1 Apr 2022 at 19:51, Victor Stinner <vstin...@python.org
<mailto:vstin...@python.org>> wrote:
> > > In Python, sadly the types.CodeType type also has a public
constructor
> > > and many projects break at each Python release because the API
> > > changes. Hopefully, it seems like the new CodeType.replace() method
> > > added to Python 3.8 mitigated the issue. IMO CodeType.replace() is a
> > > better abstraction and closer to what developers need in practice.
> >
> > It certainly has been for me. When I want to do bytecode hackery, I
> > usually start by creating a function with def/lambda, then construct a
> > modified function using f.__code__.replace(). It's the easiest way to
> > ensure that all the little details are correct.
>
> Python 3.11 added the concept of "exception table"
> (code.co_exceptiontable). You have to build this table, otherwise
> Python can no longer catch exceptions :-)
>
> I don't know how to build this exception table. It seems like
> currently there is no Python function in the stdlib to build this
> table.
>
> Example:
> ---
> def f():
> try:
> print("raise")
> raise ValueError
> except ValueError:
> print("except")
> else:
> print("else")
> print("exit func")
>
> def g(): pass
>
> if 1:
> code = f.__code__
> g.__code__ = g.__code__.replace(
> co_code=code.co_code,
> co_consts=code.co_consts,
> co_names=code.co_names,
> co_flags=code.co_flags,
> co_stacksize=code.co_stacksize)
> else:
> g.__code__ = f.__code__ # this code path works on Python 3.11
>
> g()
> ---
>
> Output with Python 3.10 (ok):
> ---
> raise
> except
> exit func
> ---
>
> Output with Python 3.11 (oops):
> ---
> raise
> Traceback (most recent call last):
> ...
> ValueError
> ---
>
> By the way, this change is not documented at all:
>
> * https://docs.python.org/dev/library/types.html#types.CodeType
<https://docs.python.org/dev/library/types.html#types.CodeType>
> * https://docs.python.org/dev/whatsnew/3.11.html
<https://docs.python.org/dev/whatsnew/3.11.html>
>
> I understand that these changes come from the "Zero cost exception
> handling" change:
> https://bugs.python.org/issue40222 <https://bugs.python.org/issue40222>
>
> Victor
> --
> Night gathers, and now my watch begins. It shall not end until my death.
--
Night gathers, and now my watch begins. It shall not end until my death.
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