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SciPy Reference Guide, Release 0.8.dev
PILED environment variable (discussed later). The cpp files are generally about 200-400 lines long and include quite
a few functions to support type conversions, etc. However, the actual compiled function is pretty simple. Below is the
familiar printf example:
>>> import weave
>>> a = 1
>>> weave.inline(’printf("%d\\n",a);’,[’a’])
1
And here is the extension function generated by inline:
static PyObject* compiled_func(PyObject*self, PyObject* args)
{
py::object return_val;
int exception_occured = 0;
PyObject *py__locals = NULL;
PyObject *py__globals = NULL;
PyObject *py_a;
py_a = NULL;
}
if(!PyArg_ParseTuple(args,"OO:compiled_func",&py__locals,&py__globals))
return NULL;
try
{
PyObject* raw_locals = py_to_raw_dict(py__locals,"_locals");
PyObject* raw_globals = py_to_raw_dict(py__globals,"_globals");
/* argument conversion code */
py_a = get_variable("a",raw_locals,raw_globals);
int a = convert_to_int(py_a,"a");
/* inline code */
/* NDARRAY API VERSION 90907 */
printf("%d\n",a); /*I would like to fill in changed locals and globals here...*/
}
catch(...)
{
return_val = py::object();
exception_occured = 1;
}
/* cleanup code */
if(!(PyObject*)return_val && !exception_occured)
{
return_val = Py_None;
}
return return_val.disown();
Every inline function takes exactly two arguments – the local and global dictionaries for the current scope. All variable
values are looked up out of these dictionaries. The lookups, along with all inline code execution, are done within
a C++ try block. If the variables aren’t found, or there is an error converting a Python variable to the appropriate
type in C++, an exception is raised. The C++ exception is automatically converted to a Python exception by SCXX
and returned to Python. The py_to_int() function illustrates how the conversions and exception handling works.
py_to_int first checks that the given PyObject* pointer is not NULL and is a Python integer. If all is well, it calls the
Python API to convert the value to an int. Otherwise, it calls handle_bad_type() which gathers information
about what went wrong and then raises a SCXX TypeError which returns to Python as a TypeError.
int py_to_int(PyObject* py_obj,char* name)
{
1.12. Weave 103