Larry Hastings <la...@hastings.org> writes:
> A comment on your approach so far: I'm very much against giving
> "default" a default value in the constructor.
You mean in the definition of the custom converter class?
> I realize that hack saves you having to say "= NULL" in a lot of
> places. But explicit is better than implicit, and we're going to read
> these signatures a lot more often than we write them, and I want
> Clinic signatures to be easy to read at first glance.
[....]
> All is not lost! What follows is rough pseudo-C code, hopefully you
> can take it from here.
>
> typedef struct {
> int set;
> time_t when;
> } clinic_time_t;
> #define DEFAULT_CLINIC_TIME_T {0, 0}
>
[...]
>
> /*[python input]
> class clinic_time_t_converter(CConverter):
> type = 'clinic_time_t'
> converter = 'parse_clinic_time_t'
> c_default = 'DEFAULT_CLINIC_TIME_T'
> [python start generated code]*/
> /*[python end generated code: checksum=...]*/
>
> Now you can use clinic_time_t. Parameters declared clinic_time_t can
> be required, or they can be optional; if they're optional give them a
> default value of None.
That doesn't work. If the default value is declared for the function
rather than in the converter definition, it overwrites the C default:
/*[clinic input]
time.gmtime
seconds: clinic_time_t=None
/
*/
gives:
static PyObject *
time_gmtime(PyModuleDef *module, PyObject *args)
{
PyObject *return_value = NULL;
clinic_time_t seconds = Py_None;
if (!PyArg_ParseTuple(args,
"|O&:gmtime",
parse_clinic_time_t, &seconds))
goto exit;
return_value = time_gmtime_impl(module, seconds);
so the default for seconds is now Py_None instead of
DEFAULT_CLINIC_TIME_T'.
Best,
Nikolaus
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