[Python-Dev] Re: Metatype conflict among bases?

David Abrahams dave@boost-consulting.com
Wed, 23 Apr 2003 08:17:15 -0400

Michael Hudson <mwh@python.net> writes:

> David Abrahams <dave@boost-consulting.com> writes:
>> Still, the message is misleading.  There's only one base class, so
>> the metatype conflict is not "among bases".
> Not arguing with that, but: what would you suggest instead?  I'm agin
> the idea of having small essays in tracebacks...

    metatype conflict: metatype of derived class B must be a
    (non-strict) subclass of the metatypes of its bases

I don't think that's too verbose.  Too many traceback messages from
Python give no indication of what the actual problem was or how to fix
it, so I don't mind getting a bit more essay-like.  Just today on
python-list I saw this

    >>> range(map(lambda x:x+1, [0, 100, 3]))
    Traceback (most recent call last):
      File "<stdin>", line 1, in ?
    TypeError: an integer is required

come up as a problem for someone.

Dave Abrahams
Boost Consulting