Re: [Cython] Rewriting/compiling parts of CPython's stdlib in Cython
On Sun, Mar 27, 2011 at 3:39 PM, Sturla Molden wrote: > Den 25.03.2011 19:03, skrev Robert Bradshaw: >> Looking at Guido's comment, Cython must be able to compile all valid Python if this will have any chance of success. >> >> Good thing that's our goal (pending an actual definition of "all valid >> Python.") >> > > In lack of a Python language specification it can be hard to tell > implementation details from syntax. It sounded though as if Guido was > worried about Cython's compatibility with Python, and maybe the Cython dev > team's attitude to Python compatibility. We are very concerned about Python compatibility. > Also don't think Cython's main strength in this context was properly > clarified in the debate. It is easy to over-focus on "speed", when it's > really a matter of "writing Python C extensions easily" -- i.e. without > knowing (a lot) about Python's C API, not having to worry about reference > counting, and the possibility of using Python code as prototype. Cython is, > without comparison, the easiest way of writing C extensions for Python. > FWIW, it's easier to use Cython than ctypes. Using Cython instead of the C > API will also avoid many programming errors, because a compiler does fewer > mistakes than a human. Those aspects are important to communicate, not just > "Cython can be as fast as C++". That is a good point. On the other hand, I don't see re-implementing working C modules written, though probably valuable from a maintenance point of view, as compelling of a use case. - Robert ___ cython-devel mailing list cython-devel@python.org http://mail.python.org/mailman/listinfo/cython-devel
Re: [Cython] cython crash: default parameters in methods of template cppclass
On Tue, Mar 22, 2011 at 7:21 AM, Simon Anders wrote: > Hi, > > I found a little bug in Cython 0.14.1. > > The following causes the Cython compiler to throw an exception: > > ---8<--- > cdef extern from "foo.h": > cdef cppclass foo[ T ]: > bar( int b = 0 ) > > cdef foo[ int ] a > a.bar( 1 ) > ---8<--- > > The exception is "AttributeError: 'CFuncType' object has no attribute > 'op_arg_struct'", thrown in line 3044, in generate_result_code. Full stack > trace attached. > > The file compiles without crash if one either > - removes the last line, i.e. the call to the class's method, or > - removes the template argument, i.e., the "[ T ]" in line 2 and > the "[ int ]" in line 5. > > Hence, the issue only appears when calling methods of _templated_ classes, > which have a _default_ value for their argument. Default arguments in C++ are completely different from default arguments in Cython, this is our bug for not catching that. You have to declare this as an overloaded method cdef extern from "foo.h": cdef cppclass foo[ T ]: bar() bar(int) Btw, unless it returns an object, you probably want to declare the return type of your methods. Perhaps we should make this a warning for extern declarations? - Robert ___ cython-devel mailing list cython-devel@python.org http://mail.python.org/mailman/listinfo/cython-devel
Re: [Cython] Rewriting/compiling parts of CPython's stdlib in Cython
Robert Bradshaw, 29.03.2011 02:09: I don't see re-implementing working C modules written, though probably valuable from a maintenance point of view, as compelling of a use case. It would be rather helpful for CPython, though. Many stdlib modules lack dedicated maintainers, and it's likely easier in the Python world to find a maintainer for code that's "mostly Python", than for code that's C plus CPython's C-API. Stefan ___ cython-devel mailing list cython-devel@python.org http://mail.python.org/mailman/listinfo/cython-devel
