Custom Exceptions Causing TypeErrors

[sommersoft]

A user in Discord brought this issue up. They receive the following exception when trying to use the library:

File "adafruit_am2320.py", line 84, in <module>
TypeError: multiple bases have instance lay-out conflict

Line 84 points to a custom exception, which came from #9. This was included in release 1.1.4 onward.

The user confirmed that release 1.1.3 does not raise the TypeError exception.

[jerryneedell]

hmm -- I reproduced this error on a few CP boards -- grandcentral, teensy 4.0
but (v1.2.1) it works fine an a Raspberry Pi 4...

reintroducing the "pass" statements does not fix it for the CP boards.
possibly a CPython incompatibility in CP?

[jepler]

Yes, it looks like this construct is not supported on CircuitPython. We're not likely to be able to add support for it, so unfortunately I don't see a way forward except for reverting it. Perhaps someone else does.

>>> class E(Exception): pass
... 
>>> class D(E, ValueError): pass
... 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: multiple bases have instance lay-out conflict

Any time an inheritance tree of classes includes more than one native base class among all its bases, this error will occur.

[jerryneedell]

I must say that this is one of most perplexing error messages I have ever received TypeError: multiple bases have instance lay-out conflict mostly due to my own ignorance of Python details, but still, could it be a bit more obtuse? ;-)

[tannewt]

Could we just have the custom Exceptions not inherit from two types? Specifically, I think we can remove AM2320Exception and just leave the stock parents.

[jerryneedell]

Could we just have the custom Exceptions not inherit from two types? Specifically, I think we can remove AM2320Exception and just leave the stock parents.

I have no idea what that means, but it sounds fine to me ;-)
I only jumped in because it was suggested that it be reverted and it was simple to do.
If you can tell me what to change, I can update the PR or feel free to take control of this.

[jerryneedell]

@tannewt ah -- I see the PR was merged -- Do you want to create a new PR to address this? Should I hold off on releasing?

[tannewt]

@jerryneedell I don't plan on making a PR but it'd be great if someone else would. I think it's ok to do a major release now to get the fix out.

[jposada202020]

According to what I see this was resolved with 1.2.2 - Reverted PR #9. If there is no disagreement I think we can proceed to close this issue

[jposada202020]

Closing. Thanks.