I'm thinking of using namedtuples in Cython -- it seems a reasonable
way to wrap a c struct, and, at least in pure python, lighter weight
than a class.
If I'm going to do that, is seems I might as well use the C-API when
constructing, rather than doing it all with the Python API. But it
appears the namedtuple is written in pure python, as a subclass of
tuple.
Which I suppose means I need to create a nametuple class with the
Python call, but then I should be able to actually set the fields with
the C-API for a tuple.
But is there any point in this anyway -- is, in fact, a cdef class
just as lightweight (or maybe more lightweight) anyway?
-Chris
--
Christopher Barker, Ph.D.
Oceanographer
Emergency Response Division
NOAA/NOS/OR&R (206) 526-6959 voice
7600 Sand Point Way NE (206) 526-6329 fax
Seattle, WA 98115 (206) 526-6317 main reception
On Thu, Sep 20, 2012 at 9:55 AM, Chris Barker <chris.bar...@noaa.gov> wrote:
> I'm thinking of using namedtuples in Cython -- it seems a reasonable
> way to wrap a c struct, and, at least in pure python, lighter weight
> than a class.
> If I'm going to do that, is seems I might as well use the C-API when
> constructing, rather than doing it all with the Python API. But it
> appears the namedtuple is written in pure python, as a subclass of
> tuple.
> Which I suppose means I need to create a nametuple class with the
> Python call, but then I should be able to actually set the fields with
> the C-API for a tuple.
> But is there any point in this anyway -- is, in fact, a cdef class
> just as lightweight (or maybe more lightweight) anyway?
A cdef class is more lightweight, but requires an explicit class for
every set of names you want. (It also has the advantage of storing
members as C values, if you intend to use them a lot from your Cython
code.)
On Thu, Sep 20, 2012 at 10:32 AM, Robert Bradshaw <rober...@gmail.com> wrote:
> A cdef class is more lightweight,
Then that's the way to go, unless there is real reason for it to be a
tuple, too.
> but requires an explicit class for
> every set of names you want.
which namedtuple requires as well, you'd still create a specific
namedtuple class for each struct you wanted to wrap.
> (It also has the advantage of storing
> members as C values, if you intend to use them a lot from your Cython
> code.)
makes sense -- and it's mutable, which more closely follows the
use-cases of C structs.
namedtuples area also sequences, but I suppose you could add that to
your cdef class if you wanted to.
Thanks -- I see now why this hasn't been done -- really no point.
-Chris
--
Christopher Barker, Ph.D.
Oceanographer
Emergency Response Division
NOAA/NOS/OR&R (206) 526-6959 voice
7600 Sand Point Way NE (206) 526-6329 fax
Seattle, WA 98115 (206) 526-6317 main reception
On Thursday, 20 September 2012 20:06:29 UTC, Chris Barker wrote: > > but requires an explicit class for > > every set of names you want.
> which namedtuple requires as well, you'd still create a specific > namedtuple class for each struct you wanted to wrap.
The difference is that a namedtuple class can be created at runtime for any set of names, whereas cdef classes can only be created for specific sets of names known at compile time. (There are probably ways around that, like generating code and cythonizing it at runtime ... but that's probably more trouble than it's worth, unless one reeeally needs dynamic cdef namedtuples)
