Robert Bradshaw wrote:
> On Aug 6, 2008, at 9:35 AM, Dag Sverre Seljebotn wrote:
>
>> Robert Bradshaw wrote:
>>> On Aug 6, 2008, at 1:49 AM, Dag Sverre Seljebotn wrote:
>>>
>>>> Obviously my past efforts weren't good enough:
>>>>
>>>> DEF MYLEN = 3
>>>> c = sizeof(MyStruct[MYLEN])
>>>>
>>>> So it seems that the parser can never discern the current syntax
>>>> (MYLEN
>>>> could have been a typedef and MyStruct and extension type, and
>>>> then it
>>>> would have been buffer syntax).
>>>>
>>>> So if keeping the current syntax, I seem to have no choice but to
>>>> create
>>>> a TrailingBracketTypeNode and delay the decision until type
>>>> analysis.
>>>> This takes some work, and adds complexity, so I want to be sure
>>>> that it
>>>> is needed first.
>>> I'm not understanding why we need to introduce a new node here, why
>>> not let the sizeof operator be OK with index nodes?
>> Yes, if you can guarantee me that the sizeof operator is the only
>> place
>> this happens, and that the sizeof name cannot ever be overriden and so
>> on, I could do that.
>>
>> The thing is, I've been bitten so many times by wrong assumptions
>> by now
>> that I'd rather use a new rule controlling the thing: If [] is used
>> on a
>> pyobject, then it is buffer, on a native type, then array. But then I
>> need to defer the resolution of what the [] means until type analysis
>> time.
>
> I think this makes sense.
To backtrack to this discussion:
- Apparently, sizeof will always be sizeof -- it is resolved in the
parser by string comparison and p_sizeof is called (it is considered an
operator, like in C).
- Also, a flag nonempty ("context requires that some variable name is
present") is passed to the type parsing code, which is set to True in
the kind of situations Lisandro Dalcin reported.
So the fix was really easy, in the parser only, and I didn't attempt the
much more complicated solution outlined earlier.
(BTW, an assumption made by this is that we don't allow
cdef external_func(object[int])
I.e. if exporting a function using a buffer, you must do
pxd file:
cdef myfunc(object)
pyx file:
cdef myfunc(object[int] param): ...
This makes kind of sense as the caller knows nothing about the buffer
access anyway, it's an implementation shorthand. If it is too
inconvenient we could work around it later but the changes are quite
extensive and I'd rather do more useful stuff. BTW this was already
explictly disallowed in existing buffer code, so only the error message
changes by this.)
--
Dag Sverre
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