metaclass conflict

[petar.m....@gmail.com]

I try to run example from ch3 and I got this error:

Traceback (most recent call last):

  File "/Users/*/opencvbook/opencv-python-blueprints/chapter3/chapter3.py", line 15, in <module>

    from gui import BaseLayout

  File "/Users/*/opencvbook/opencv-python-blueprints/chapter3/gui.py", line 15, in <module>

    class BaseLayout(wx.Frame):

  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/abc.py", line 87, in __new__

    cls = super(ABCMeta, mcls).__new__(mcls, name, bases, namespace)

TypeError: Error when calling the metaclass bases

    metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases

[Michael Beyeler]

Aaaah, the ominous metaclass type conflict error. :)

You could try editing gui.py the following way. Change

class BaseLayout(wx.Frame):

to

class BaseLayout(Meta1):

Then add a new class right before that:

class Meta1(wx.Frame):

     pass

In addition, the 2nd edition of the book should provide a more modern solution: https://github.com/PacktPublishing/OpenCV-4-with-Python-Blueprints-Second-Edition/blob/master/wx_gui.py

Best,

Michael

[Michael Beyeler]

FYI, this issue has been fixed as of commit f7fe25f.

On Tuesday, November 8, 2016 at 2:46:46 PM UTC-8, Michael Beyeler wrote:

Aaaah, the ominous metaclass type conflict error. :)

You could try editing gui.py the following way. Change

class BaseLayout(wx.Frame):

to

class BaseLayout(Meta1):

Then add a new class right before that:

class Meta1(wx.Frame):

     pass

Either way seems to work fine on Ubuntu 14 / Windows 10 with Python 2.7. What platform are you on?

Let me know how it goes.

[zh...@string.co]

Hi Michael,

I still get the same error from the latest change on Mac with python 2.7 and latest wx

On Tuesday, 8 November 2016 22:46:46 UTC, Michael Beyeler wrote:

Aaaah, the ominous metaclass type conflict error. :)

You could try editing gui.py the following way. Change

class BaseLayout(wx.Frame):

to

class BaseLayout(Meta1):

Then add a new class right before that:

class Meta1(wx.Frame):

     pass

Either way seems to work fine on Ubuntu 14 / Windows 10 with Python 2.7. What platform are you on?

Let me know how it goes.

[Michael Beyeler]

That's too bad to hear, but thanks for the heads-up!

I am now using the `six` module to do a Python2/3 compatible metaclass import. Can you check e.g. Chapter 1 to see if this works for you? (Sorry, I don't have a Mac to play around with.)

Alternatively, Chapter 7 uses a different methodology (user-contributed) that is supposed to get rid of the conflict. Does that work on your platform?

Best,

Michael

[Jug]

Hi Michael,

I'm getting this with Chapter 1 for both python2 & python3.  Running macOS 10.13.6

Any tips would be appreciated. 

Thanks,

J

TypeError: metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases

[Charles Masenas]

MacOS 10.15.5, Python 3 and getting same error.  Ideas?

[Michael Beyeler]

The second edition of the book should provide a more modern solution: https://github.com/PacktPublishing/OpenCV-4-with-Python-Blueprints-Second-Edition/blob/master/wx_gui.py