[Cython] Builtin declarations + should BufferException be backported?

[Dag Sverre Seljebotn]

Robert Bradshaw wrote:
> On Sep 17, 2008, at 3:57 AM, Dag Sverre Seljebotn wrote:
>   
>
>> Slightly related, look at this code in Symtab.py:
>> def declare_builtin(self, name, pos):
>>     if not hasattr(__builtin__, name):
>>
>> If I'm not entirely wrong, this means that BufferError (and other new
>> builtin symbols) will be available only if you run Cython under Python
>> 2.6+. I find the fact that results of a compilation depends on the
>> Python version used for running Cython somewhat disturbing. Should
>> perhaps a literal list of accepted Cython builtins be present in
>> Symtab.py instead? (Or couple it to Builtins.py somehow?)
>>     
>
> I think maintaining such a list would be less elegant than looking  
> them up at runtime, especially as it is fairly stable and  
> monotonically increasing. If one wants to use the code with, say,  
> Python 2.3, then one simply has to avoid using newer symbols in ones  
> code (just as with Python), and it is easy to check (just compile  
> with Python 2.3). This allows people to write code with newer  
> builtins if one wants without having to maintain a list of when every  
> symbol was introduced.
>   
I might have misunderstood some earlier discussions then. So, in effect, 
one has to run cython.py using an interpreter that has at least the same 
Python version as the builtins you are using.

Well, I can certainly live with that. But I think it kind of contradicts 
what Stefan has tried to achieve with 3.0 compatability etc. (i.e one 
then has to use Python 2.6 if one wants to compile Cython code for 
Python 3.0 using BufferError...)

Can't this just be deferred until run-time anyway? I.e. have the list in 
question be the set of all strings :-) I don't think there's a strong 
reason we have to have a compile-time error here? Then sys.version_info 
etc. could be used to create code that runs on multiple targets (and 
compile, using Cython, under multiple targets!) just like in Python.

Dag Sverre