> On Nov 9, 2017, at 2:44 AM, Serhiy Storchaka <storch...@gmail.com> wrote:
>
> If the problem is with naming, what names do you prefer? This already was
> bikeshedded (I insisted on discussing names before introducing the macros),
> but may now you have better ideas?
It didn't really seem like a bad idea until after you swept through the code
with 200+ applications of the macro and I saw how unclear the results were.
Even code that I wrote myself is now harder for me to grok (for example, the
macro was applied 17 times to already correct code in itertools).
We used to employ a somewhat plain coding style that was easy to walk through,
but the following examples seem opaque. I find it takes practice to look at any
one of these and say that it is unequivocally correct (were the function error
return arguments handled correctly, are the typecasts proper, at what point can
a reentrant call occur, which is the source operand and which is the
destination, is the macro using either of the operands twice, is the
destination operand an allowable lvalue, do I need to decref the source operand
afterwards, etc):
Py_SETREF(((PyHeapTypeObject*)type)->ht_name, value)
Py_SETREF(newconst, PyFrozenSet_New(newconst));
Py_XSETREF(c->u->u_private, s->v.ClassDef.name);
Py_SETREF(*p, t);
Py_XSETREF(self->lineno, PyTuple_GET_ITEM(info, 1));
Py_SETREF(entry->path, PyUnicode_EncodeFSDefault(entry->path));
Py_XSETREF(self->checker, PyObject_GetAttrString(ob, "_check_retval_"));
Py_XSETREF(fut->fut_source_tb,
_PyObject_CallNoArg(traceback_extract_stack));
Stylistically, all of these seem awkward and I think there is more to it than
just the name. I'm not sure it is wise to pass complex inputs into a
two-argument macro that makes an assignment and has a conditional refcount
side-effect. Even now, one of the above looks to me like it might not be
correct.
Probably, we're the wrong people to be talking about this. The proposal is to
make these macros part of the official API so that it starts to appear in
source code everywhere. The question isn't whether the above makes sense to
you and me; instead, it is whether other people can make heads or tails out the
above examples. As a result of making the macros official, will the Python
world have a net increase in complexity or decrease in complexity?
My personal experience with the macros hasn't been positive. Perhaps everyone
else thinks it's fine. If so, I won't stand in your way.
Raymond
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