cython tutorial and transfer btstack lib as a pyd library

cython good tutorial

https://nyu-cds.github.io/python-cython/

cython tutorial

http://apprize.info/python/cython/index.html

http://cython.readthedocs.io/en/latest/src/userguide/extension_types.html

cython faq

https://github.com/cython/cython/wiki/FAQ

tutorial pdf

https://media.readthedocs.org/pdf/cython/stable/cython.pdf

Study Record

20170924 use callback sample to do a function table

1. use ctypedef to declear the prototype of a function or a type

   cdef extern from "cheesefinder.h":
    ctypedef void (*cheesefunc)(char *name, void *user_data)
    ctypedef struct cheesetable:
        pass
   

2. global variable / struct global variable could be declear inside pyx file but you need to have the typedef first

   cdef cheesefunc g_table3
   

   should have ‘cheesetable’ type , come from ‘extern from a prototpe file’

   cdef extern from "cheesefinder.h":
    ctypedef void (*cheesefunc)(char *name, void *user_data)
   

3. all code inside pyx are python protoype and have primitive of c-lang type. It only has ‘char *’, ‘void *’, ‘int’ for declear. inside code body, it still uses python style and code. you needs ‘global ' to access the global variable of python.

   cdef int mycalclen(char *name, void *f):
    global prefix  # for example: "value-len:"
    l = 0
    if name:
        l = len(name.decode('utf-8'))
    print("inside mycalclen " + prefix + str(l))
    return l
   

string array sample

• from python-list to char** https://stackoverflow.com/questions/17511309/fast-string-array-cython

  from cpython.string cimport PyString_AsString
  cdef char ** to_cstring_array(list_str):
    cdef char **ret = <char **>malloc(len(list_str) * sizeof(char *))
    for i in xrange(len(list_str)):
        ret[i] = PyString_AsString(list_str[i])
    return ret
  

if missing ‘from cpython.string import PyString_AsString’, only got the wrong message

gap_if.pyx:31:34: Storing unsafe C derivative of temporary Python reference

• where is the PyString_AsString https://mail.python.org/pipermail/python-list/2009-March/527813.html

Misc

1. string buffer example
2. lifetime example
3. how to design interface - structure for a few information
4. https://github.com/karulis/pybluez/blob/master/msbt/_msbt.c

QnA

1. reference count problem => see generate .c files