I don't see how, since the L(B*)'s are listed in order in the argument list: L(B1), L(B2), ..., and each L(B*) starts with B*: L(B1) = <B1, ...>, L(B2) = <B2, ...>, ...
Could you please give a counter-example? On Tue, Aug 15, 2017 at 9:44 PM, Ian Kelly <ian.g.ke...@gmail.com> wrote: > > On Tue, Aug 15, 2017 at 9:56 AM, Evan Aad <oddevene...@gmail.com> wrote: > > According to the description of Python's method resolution order (mro) > > (https://www.python.org/download/releases/2.3/mro/), a.k.a. C3 > > linearization (see Wikipedia), the algorithm can be described as > > follows: > > > > "the linearization of C is the sum of C plus the merge of the > > linearizations of the parents and the list of the parents." > > > > Symbolically, the algorithm is defined recursively thus: > > > > L(O) = <O> > > L(C) = <C> + merge(L(B1),..., L(Bn), <B1,...,Bn>) > > > > where > > > > * O is the class from which every class inherits. > > * C is a class that inherits directly from B1, ..., Bn, in this order. > > * < and > are list delimiters. > > * + is the list-concatenation operator. > > * 'merge' merges its list arguments into a single list with no > > repetitions in the manner described in the next paragraph. > > > > Consider the head of the first list, i.e L(B1)[0]: if it is a good > > head, i.e. if it is not in the proper tail of any of the other lists, > > add it to the linearization of C, and remove it from all the lists in > > the merge. Otherwise, consider the head of the next list, etc. Repeat > > until no more classes, or no good heads. In the latter case, it is > > impossible to construct the merge. > > > > > > > > Why is the list <B1,...,Bn> of parents given as an argument to > > 'merge'? Will the algorithm produce different results if this argument > > is omitted? > > It ensures that the parents are linearized in that order. Without that > list, it would be possible for B2 to appear before B1 in the MRO of C. > -- > https://mail.python.org/mailman/listinfo/python-list -- https://mail.python.org/mailman/listinfo/python-list
