[Cython] Visitors and compiling Cython in Cython

[Stefan Behnel]

Hi,

Dag Sverre Seljebotn wrote:
> I'll quote Gary so you have the context:
> 
> """
> Efficiency does matter to Sage though, and an O(1) overhead is very
> far from negligible.  Cython uses real C vtables, so there are
> absolutely no dict-based lookups involved with cdef class
> polymorphism.  -Infinity to any proposal that makes code slower.
> 
> <new post>
> 
> Well, clarifying what I meant a bit more, the *biggest* speed loss
> anywhere is dictionary lookups.  If your going to use dictionary
> lookups at object time, you lose most of the advantage of using cython
> to compile cython.
> """

I don't think the intention to compile Cython should impact our design
decisions. If a Cython compiled Cython compiler is not any faster than a
Python based one, then that's a reason to improve Cython, not its code.

Stefan