def _infer_from_metaclass_constructor(cls, func):
"""Try to infer what the given *func* constructor is building
:param astroid.FunctionDef func:
A metaclass constructor. Metaclass definitions can be
functions, which should accept three arguments, the name of
the class, the bases of the class and the attributes.
The function could return anything, but usually it should
be a proper metaclass.
:param astroid.ClassDef cls:
The class for which the *func* parameter should generate
a metaclass.
:returns:
The class generated by the function or None,
if we couldn't infer it.
:rtype: astroid.ClassDef
"""
context = astroid.context.InferenceContext()
class_bases = astroid.List()
class_bases.postinit(elts=cls.bases)
attrs = astroid.Dict()
local_names = [(name, values[-1]) for name, values in cls.locals.items()]
attrs.postinit(local_names)
builder_args = astroid.Tuple()
builder_args.postinit([cls.name, class_bases, attrs])
context.callcontext = astroid.context.CallContext(builder_args)
try:
inferred = next(func.infer_call_result(func, context), None)
except astroid.InferenceError:
return None
return inferred or None
def tuple_node(draw, elt=const_node, **kwargs):
"""Return a Tuple node with elements drawn from elt.
"""
elts = draw(hs.lists(elt(), **kwargs))
node = astroid.Tuple()
node.postinit(elts)
return node