def transform_type_def(self, tdef: TypeDef) -> List[Node]:
"""Transform a type definition.
The result may be one or two definitions. The first is the
transformation of the original TypeDef. The second is a
wrapper type, which is generated for generic types only.
"""
defs = [] # type: List[Node]
if tdef.info.type_vars:
# This is a generic type. Insert type variable slots in
# the class definition for new type variables, i.e. type
# variables not mapped to superclass type variables.
defs.extend(self.make_tvar_representation(tdef.info))
# Iterate over definitions and transform each of them.
vars = set() # type: Set[Var]
for d in tdef.defs.body:
if isinstance(d, FuncDef):
# Implicit cast from FuncDef[] to Node[] is safe below.
defs.extend(Any(self.func_tf.transform_method(d)))
elif isinstance(d, VarDef):
defs.extend(self.transform_var_def(d))
for n in d.items:
vars.add(n)
elif isinstance(d, AssignmentStmt):
self.transform_assignment(d)
defs.append(d)
# Add accessors for implicitly defined attributes.
for node in tdef.info.names.values():
if isinstance(node.node, Var):
v = cast(Var, node.node)
if v.info == tdef.info and v not in vars:
defs.extend(self.make_accessors(v))
# For generic classes, add an implicit __init__ wrapper.
defs.extend(self.make_init_wrapper(tdef))
if tdef.is_generic() or (tdef.info.bases and
tdef.info.mro[1].is_generic()):
self.make_instance_tvar_initializer(
cast(FuncDef, tdef.info.get_method('__init__')))
if not defs:
defs.append(PassStmt())
if tdef.is_generic():
gen_wrapper = self.generic_class_wrapper(tdef)
tdef.defs = Block(defs)
dyn_wrapper = self.make_type_object_wrapper(tdef)
if not tdef.is_generic():
return [tdef, dyn_wrapper]
else:
return [tdef, dyn_wrapper, gen_wrapper]
def make_init_wrapper(self, tdef: TypeDef) -> List[Node]:
"""Make and return an implicit __init__ if class needs it.
Otherwise, return an empty list. We include an implicit
__init__ if the class is generic or if it extends a generic class
and if it does not define __init__.
The __init__ of a generic class requires one or more extra type
variable arguments. The inherited __init__ may not accept these.
For example, assume these definitions:
. class A(Generic[T]): pass
. class B(A[int]): pass
The constructor for B will be (equivalent to)
. def __init__(self: B) -> None:
. self.__tv = <int>
. super().__init__(<int>)
"""
# FIX overloading, default args / varargs, keyword args
info = tdef.info
if '__init__' not in info.names and (
tdef.is_generic() or (info.bases and
info.mro[1].is_generic())):
# Generic class with no explicit __init__ method
# (i.e. __init__ inherited from superclass). Generate a
# wrapper that initializes type variable slots and calls
# the superclass __init__ method.
base = info.mro[1]
selftype = self_type(info)
callee_type = cast(Callable, analyse_member_access(
'__init__', selftype, None, False, True, None, None,
base))
# Now the callee type may contain the type variables of a
# grandparent as bound type variables, but we want the
# type variables of the parent class. Explicitly set the
# bound type variables.
callee_type = self.fix_bound_init_tvars(callee_type,
map_instance_to_supertype(selftype, base))
super_init = cast(FuncDef, base.get_method('__init__'))
# Build argument list.
args = [Var('self')]
for i in range(1, len(super_init.args)):
args.append(Var(super_init.args[i].name()))
args[-1].type = callee_type.arg_types[i - 1]
selft = self_type(self.tf.type_context())
callee_type = prepend_arg_type(callee_type, selft)
creat = FuncDef('__init__', args,
super_init.arg_kinds, [None] * len(args),
Block([]))
creat.info = tdef.info
creat.type = callee_type
creat.is_implicit = False
tdef.info.names['__init__'] = SymbolTableNode(MDEF, creat,
typ=creat.type)
# Insert a call to superclass constructor. If the
# superclass is object, the constructor does nothing =>
# omit the call.
if base.fullname() != 'builtins.object':
creat.body.body.append(
self.make_superclass_constructor_call(tdef.info,
callee_type))
# Implicit cast from FuncDef[] to Node[] is safe below.
return Any(self.func_tf.transform_method(creat))
else:
return []