Mailing List Archive: Re: [std-proposals] Exception compatibility with aliens

Re: [std-proposals] Exception compatibility with aliens

Jan 18, 2023, 2:04 AM

Post #1 of 4 (239 views)

On Wed, 18 Jan 2023 at 11:45, Frederick Virchanza Gotham via
Std-Proposals <std-proposals@lists.isocpp.org> wrote:
>
> I have sent this email to two mailing lists for programming language
> proposals, the one for C++ and the one for Python. If you reply to
> this email, please make sure you reply to both. You can see the
> mailing list archives for this month for each list here:
>
> C++ : https://lists.isocpp.org/std-proposals/2023/01/date.php
> Python : https://mail.python.org/archives/list/python-dev@python.org/2023/1/
>
> Both C++ and Python have exception handling, however a C++ program
> which links with a Python library is unable to handle an exception
> thrown from Python.

Perhaps you should just use
https://www.boost.org/doc/libs/1_81_0/libs/python/doc/html/index.html

See also https://realpython.com/python-bindings-overview/

In both C++ and Python, exceptions can contain anything as their
payload. The problem becomes a problem of
mapping one language to the other, not just mapping exceptions. That
makes it a general cross-language binding generation problem,
so the forthcoming reflection/injection in C++ can certainly help, but
just having a 'list' of exceptions isn't going to
cut it either way.
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Re: [std-proposals] Exception compatibility with aliens [ In reply to ]

cauldwell.thomas at gmail

Jan 18, 2023, 7:35 AM

Post #2 of 4 (239 views)

Permalink

On Wed, Jan 18, 2023 at 3:07 PM Jason McKesson wrote:
>
> Also, this proposal seems to be missing the biggest issue with
> cross-language exception handling: the fact that you can't throw
> exceptions across languages. The only thing you *can* do is catch
> exceptions on the source language end, convert them into some data
> packet, and throw a different exception on the destination language
> side.

Yes this is what I had in mind. Behind the scenes, the C++ compiler
would catch the Python exception and then throw something that C++ can
deal with "such as std::aliens::python::exception".
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Re: [std-proposals] Exception compatibility with aliens [ In reply to ]

barry at barrys-emacs

Jan 18, 2023, 1:13 PM

Post #3 of 4 (239 views)

Permalink

> On 18 Jan 2023, at 15:35, Frederick Virchanza Gotham <cauldwell.thomas@gmail.com> wrote:
>
> On Wed, Jan 18, 2023 at 3:07 PM Jason McKesson wrote:
>>
>> Also, this proposal seems to be missing the biggest issue with
>> cross-language exception handling: the fact that you can't throw
>> exceptions across languages. The only thing you *can* do is catch
>> exceptions on the source language end, convert them into some data
>> packet, and throw a different exception on the destination language
>> side.
>
>
> Yes this is what I had in mind. Behind the scenes, the C++ compiler
> would catch the Python exception and then throw something that C++ can
> deal with "such as std::aliens::python::exception".

In PyCXX I allows exceptions to go into and out of python and C++.
https://cxx.sourceforge.net/

You can raise in C++ go into python and back into C++ and the exception arrives as expected.
You can riase in Python fo into C++ and back to Python and again the exception arrives as expected.
That is as long as its a python exception.

Barry

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Re: [std-proposals] Exception compatibility with aliens [ In reply to ]

josh.engroff at gmail

Jan 18, 2023, 3:54 PM

Post #4 of 4 (239 views)

Permalink

Table this, perhaps?

> On Jan 18, 2023, at 5:04 PM, Barry Scott <barry@barrys-emacs.org> wrote:
>
> ?
>
>> On 18 Jan 2023, at 15:35, Frederick Virchanza Gotham <cauldwell.thomas@gmail.com> wrote:
>>
>>> On Wed, Jan 18, 2023 at 3:07 PM Jason McKesson wrote:
>>>
>>> Also, this proposal seems to be missing the biggest issue with
>>> cross-language exception handling: the fact that you can't throw
>>> exceptions across languages. The only thing you *can* do is catch
>>> exceptions on the source language end, convert them into some data
>>> packet, and throw a different exception on the destination language
>>> side.
>>
>>
>> Yes this is what I had in mind. Behind the scenes, the C++ compiler
>> would catch the Python exception and then throw something that C++ can
>> deal with "such as std::aliens::python::exception".
>
> In PyCXX I allows exceptions to go into and out of python and C++.
> https://cxx.sourceforge.net/
>
> You can raise in C++ go into python and back into C++ and the exception arrives as expected.
> You can riase in Python fo into C++ and back to Python and again the exception arrives as expected.
> That is as long as its a python exception.
>
> Barry
>
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>> Code of Conduct: http://python.org/psf/codeofconduct/
>>
>
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