def check_and_find_best_base(space, bases_w):
"""The best base is one of the bases in the given list: the one
whose layout a new type should use as a starting point.
This version checks that bases_w is an acceptable tuple of bases.
"""
w_bestbase = find_best_base(space, bases_w)
if w_bestbase is None:
raise OperationError(space.w_TypeError,
space.wrap("a new-style class can't have "
"only classic bases"))
if not w_bestbase.instancetypedef.acceptable_as_base_class:
raise operationerrfmt(space.w_TypeError,
"type '%N' is not an "
"acceptable base class",
w_bestbase)
# check that all other bases' layouts are superclasses of the bestbase
w_bestlayout = w_bestbase.w_same_layout_as or w_bestbase
for w_base in bases_w:
if isinstance(w_base, W_TypeObject):
w_layout = w_base.w_same_layout_as or w_base
if not issublayout(w_bestlayout, w_layout):
raise OperationError(space.w_TypeError,
space.wrap("instance layout conflicts in "
"multiple inheritance"))
return w_bestbase
def issublayout(w_layout1, w_layout2):
space = w_layout2.space
while w_layout1 is not w_layout2:
w_layout1 = find_best_base(space, w_layout1.bases_w)
if w_layout1 is None:
return False
w_layout1 = w_layout1.w_same_layout_as or w_layout1
return True
def get_parent_layout(w_type):
"""Compute the most parent class of 'w_type' whose layout
is the same as 'w_type', or None if all parents of 'w_type'
have a different layout than 'w_type'.
"""
w_starttype = w_type
while len(w_type.bases_w) > 0:
w_bestbase = find_best_base(w_type.space, w_type.bases_w)
if w_type.instancetypedef is not w_bestbase.instancetypedef:
break
if w_type.nslots != w_bestbase.nslots:
break
w_type = w_bestbase
if w_type is not w_starttype:
return w_type
else:
return None
def best_base(space, bases_w):
if not bases_w:
return None
return find_best_base(bases_w)
def descr__base(space, w_type):
from pypy.objspace.std.typeobject import find_best_base
w_type = _check(space, w_type)
return find_best_base(space, w_type.bases_w)
def best_base(space, bases_w):
if not bases_w:
return None
return find_best_base(bases_w)
def descr__base(space, w_type):
from pypy.objspace.std.typeobject import find_best_base
w_type = _check(space, w_type)
return find_best_base(space, w_type.bases_w)
