[pypy-dev] clarification cffi vs _ffi_ vs _ffi vs libffi vs _rawffi vs rffi
arigo at tunes.org
Wed Nov 27 17:24:10 CET 2013
On Wed, Nov 27, 2013 at 4:07 PM, Dima Tisnek <dimaqq at gmail.com> wrote:
> there seems to be some confusion (could be all mine) between N terms
> related to FFI:
As a user of PyPy you only need to concern yourself with cffi and
ctypes. The rest is all a number of more-or-less related internal
sub-parts of PyPy or the RPython translation toolchain that all
attempt to do accessing C-level functionality: rffi, _ffi, _rawffi.
And libffi is the existing, non-PyPy-related, C library that is
(sometimes) used by these other levels.
> docs in question:
"rffi" is about writing RPython code, e.g. a special extension module
for PyPy; in most cases you don't need that. The page
http://doc.pypy.org/en/latest/extending.html is a bit outdated :-(
Thanks for pointing it out.
> in my own testing, I noticed that equivalent code cffi code is faster
> than ctypes, is there an explanation for this?
On top of PyPy, yes, definitely. CFFI is simpler than ctypes; it was
*designed* to be simple. Although it was not particularly designed
for PyPy and works fine on CPython (and was actually first developed
for CPython), this has the intended benefit that PyPy's JIT can do a
good job on it.
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