[Python-Dev] python and super (original) (raw)

Greg Ewing greg.ewing at canterbury.ac.nz
Sat Apr 16 01:48:54 CEST 2011

Mark Shannon wrote:

class A: pass class B(A): pass class C(A,B):pass Traceback (most recent call last): File "", line 1, in TypeError: Cannot create a consistent method resolution order (MRO) for bases B, A

All right, but this is okay:

class C(B, A): pass

Michael Foord wrote:

For a super call in C, B is a sibling to A. For a super call in B, A is a parent.

With the semantics I was suggesting if C calls super, but A doesn't then B would still get called.

which is contradicted by:

"Siblings", in the context of a single MRO are thus classes between which there is no sub-class/super-class relation.

So I maintain that the situation is far from clear. :-)

-- Greg

More information about the Python-Dev mailing list