- if __getattribute__ exists, it is called first;
if it doesn't exists, PyObject_GenericGetAttr is called first.
- if the above raises AttributeError, and __getattr__ exists,
it is called.
classes to __getattribute__, to make it crystal-clear that it doesn't
have the same semantics as overriding __getattr__ on classic classes.
This is a halfway checkin -- I'll proceed to add a __getattr__ hook
that works the way it works in classic classes.
no backwards compatibility to worry about, so I just pushed the
'closure' struct member to the back -- it's never used in the current
code base (I may eliminate it, but that's more work because the getter
and setter signatures would have to change.)
As examples, I added actual docstrings to the getset attributes of a
few types: file.closed, xxsubtype.spamdict.state.
compatibility, this required all places where an array of "struct
memberlist" structures was declared that is referenced from a type's
tp_members slot to change the type of the structure to PyMemberDef;
"struct memberlist" is now only used by old code that still calls
PyMember_Get/Set. The code in PyObject_GenericGetAttr/SetAttr now
calls the new APIs PyMember_GetOne/SetOne, which take a PyMemberDef
argument.
As examples, I added actual docstrings to the attributes of a few
types: file, complex, instance method, super, and xxsubtype.spamlist.
Also converted the symtable to new style getattr.
hack, and it's even more disgusting than a PyInstance_Check() call.
If the tp_compare slot is the slot used for overrides in Python,
it's always called.
Add some tests that show what should work too.
only safely call a type's tp_compare slot if the second argument is
also an instance of the same type. I hate to think what
e.g. int_compare() would do with a second argument that's a float!
NotImplemented when the lookup fails, and use this for binary
operators. Also lookup_maybe() which doesn't raise an exception when
the lookup fails (still returning NULL).
- Don't turn a non-tuple argument into a one-tuple. Rather, the
caller must pass a format that causes Py_VaBuildValue() to return a
tuple.
- Speed things up by calling PyObject_Call (which is fairly low-level
and straightforward) rather than PyObject_CallObject (which calls
PyEval_CallObjectWithKeywords which calls PyObject_Call, and nothing
is really done in the mean time except some tests for NULL args and
valid types, which are already guaranteed).
- Cosmetics.
Other places:
- Make sure that the format argument to call_method() is surrounded by
parentheses, so it will cause a tuple to be created.
- Replace a few calls to PyEval_CallObject() with a surefire tuple for
args to calls to PyObject_Call(). (A few calls to
PyEval_CallObject() remain that have NULL for args.)
on to the tp_new slot (if non-NULL), as well as to the tp_init slot (if
any). A sane type implementing both tp_new and tp_init should probably
pay attention to the arguments in only one of them.
iterable object. I'm not sure how that got overlooked before!
Got rid of the internal _PySequence_IterContains, introduced a new
internal _PySequence_IterSearch, and rewrote all the iteration-based
"count of", "index of", and "is the object in it or not?" routines to
just call the new function. I suppose it's slower this way, but the
code duplication was getting depressing.
a->tp_mro. If a doesn't have class, it's considered a subclass only
of itself or of 'object'.
This one fix is enough to prevent the ExtensionClass test suite from
dumping core, but that doesn't say much (it's a rather small test
suite). Also note that for ExtensionClass-defined types, a different
subclass test may be needed. But I haven't checked whether
PyType_IsSubtype() is actually used in situations where this matters
-- probably it doesn't, since we also don't check for classic classes.
__dict__ slot for string subtypes.
subtype_dealloc(): properly use _PyObject_GetDictPtr() to get the
(potentially negative) dict offset. Don't copy things into local
variables that are used only once.
type_new(): properly calculate a negative dict offset when tp_itemsize
is nonzero. The __dict__ attribute, if present, is now a calculated
attribute rather than a structure member.
don't use getattr, but only look in the dict of the type and base types.
This prevents picking up all sorts of weird stuff, including things defined
by the metaclass when the object is a class (type).
For this purpose, a helper function lookup_method() was added. One or two
other places also use this.
super(type) -> unbound super object
super(type, obj) -> bound super object; requires isinstance(obj, type)
Typical use to call a cooperative superclass method:
class C(B):
def meth(self, arg):
super(C, self).meth(arg);
interpretation of negative indices, since neither the sq_*item slots
nor the slot_ wrappers do this. (Slices are a different story, there
the size wrapping is done too early.)
Classes that don't use __slots__ have a __weakref__ member added in
the same way as __dict__ is added (i.e. only if the base didn't
already have one). Classes using __slots__ can enable weak
referenceability by adding '__weakref__' to the __slots__ list.
Renamed the __weaklistoffset__ class member to __weakrefoffset__ --
it's not always a list, it seems. (Is tp_weaklistoffset a historical
misnomer, or do I misunderstand this?)
the class dict). Anything but a nonnegative int in either place is
*ignored* (before, a non-Boolean was an error). The default is still
static -- in a comparative test, Jeremy's Tools/compiler package ran
twice as slow (compiling itself) using dynamic as the default. (The
static version, which requires a few tweaks to avoid modifying class
variables, runs at about the same speed as the classic version.)
slot_tp_descr_get(): this also needed fallback behavior.
slot_tp_getattro(): remove a debug fprintf() call.
the metatype passed in as an argument. This prevents infinite
recursion when a metatype written in Python calls type.__new__() as a
"super" call.
Also tweaked some comments.
- type_module(), type_name(): if tp_name contains one or more period,
the part before the last period is __module__, the part after that
is __name__. Otherwise, for non-heap types, __module__ is
"__builtin__". For heap types, __module__ is looked up in
tp_defined.
- type_new(): heap types have their __module__ set from
globals().__name__; a pre-existing __module__ in their dict is not
overridden. This is not inherited.
- type_repr(): if __module__ exists and is not "__builtin__", it is
included in the string representation (just as it already is for
classes). For example <type '__main__.C'>.
- descrobject.c:descr_check(): only believe None means the same as
NULL if the type given is None's type.
- typeobject.c:wrap_descr_get(): don't "conventiently" default an
absent type to the type of the object argument. Let the called
function figure it out.
operators for which a default implementation exist now work, both in
dynamic classes and in static classes, overridden or not. This
affects __repr__, __str__, __hash__, __contains__, __nonzero__,
__cmp__, and the rich comparisons (__lt__ etc.). For dynamic
classes, this meant copying a lot of code from classobject! (XXX
There are still some holes, because the comparison code in object.c
uses PyInstance_Check(), meaning new-style classes don't get the
same dispensation. This needs more thinking.)
- Add object.__hash__, object.__repr__, object.__str__. The __str__
dispatcher now calls the __repr__ dispatcher, as it should.
- For static classes, the tp_compare, tp_richcompare and tp_hash slots
are now inherited together, or not at all. (XXX I fear there are
still some situations where you can inherit __hash__ when you
shouldn't, but mostly it's OK now, and I think there's no way we can
get that 100% right.)
XXX There are still some loose ends: repr(), str(), hash() and
comparisons don't inherit a default implementation from object. This
must be resolved similarly to the way it's resolved for classic
instances.
XXX This is not sufficient: if a dynamic class has no __repr__ method
(for instance), but later one is added, that doesn't add a tp_repr
slot, so repr() doesn't call the __repr__ method. To make this work,
I'll have to add default implementations of several slots to 'object'.
XXX Also, dynamic types currently only inherit slots from their
dominant base.
problem). inherit_slots() is split in two parts: inherit_special()
which inherits the flags and a few very special members from the
dominant base; inherit_slots() which inherits only regular slots,
and is now called for each base in the MRO in turn. These are now
both void functions since they don't have error returns.
- Added object.__setitem__() back -- for the same reason as
object.__new__(): a subclass of object should be able to call
object.__new__().
- add_wrappers() was moved around to be closer to where it is used (it
was defined together with add_methods() etc., but has nothing to do
with these).
bit. For one, this class:
class C(object):
def __new__(myclass, ...): ...
would have no way to call the __new__ method of its base class, and
the workaround (to create an intermediate base class whose __new__ you
can call) is ugly.
So, I've come up with a better solution that restores object.__new__,
but still solves the original problem, which is that built-in and
extension types shouldn't inherit object.__new__. The solution is
simple: only "heap types" inherit tp_new. Simpler, less code,
perfect!
division. The basic binary operators now all correctly call the
__rxxx__ variant when they should.
In type_new(), I now make the new type a new-style number unless it
inherits from an old-style number that has numeric methods.
By way of cosmetics, I've changed the signatures of the SLOT<i> macros
to take actual function names and operator names as strings, rather
than rely on C preprocessor symbol manipulations. This makes the
calls slightly more verbose, but greatly helps simple searches through
the file: you can now find out where "__radd__" is used or where the
function slot_nb_power() is defined and where it is used.
- Add an explicit call to PyType_Ready(&PyList_Type) to pythonrun.c
(just for the heck of it, really -- we should either explicitly
ready all types, or none).
- Add comment blocks explaining add_operators() and override_slots().
(This file could use some more explaining, but this is all I had
breath for today. :)
- Renamed the argument 'base' of add_wrappers() to 'wraps' because
it's not a base class (which is what the 'base' identifier is used
for elsewhere).
Small nits:
- Fix add_tp_new_wrapper() to avoid overwriting an existing __new__
descriptor in tp_defined.
- In add_operators(), check the return value of add_tp_new_wrapper().
Functional change:
- Remove the tp_new functionality from PyBaseObject_Type; this means
you can no longer instantiate the 'object' type. It's only useful
as a base class.
- To make up for the above loss, add tp_new to dynamic types. This
has to be done in a hackish way (after override_slots() has been
called, with an explicit call to add_tp_new_wrapper() at the very
end) because otherwise I ran into recursive calls of slot_tp_new().
Sigh.
Guido van Rossum
Tim Peters
Neil Schemenauer
Barry Warsaw
Martin v. Löwis
Jack Jansen