Larry Hastings <la...@hastings.org> writes:
> 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}
>
> static int
> parse_clinic_time_t_arg(PyObject *arg, clinic_time_t *ct)
> {
> if (arg == NULL)
> return 1;
> if (arg == Py_None)
> return 0;
> if (_PyTime_ObjectToTime_t(arg, &ct->when) == -1) {
> set = 1;
> return 0;
> }
> return 1;
> }
>
> static int post_parse_clinic_time_t(clinic_time_t *ct) {
> if (ct->set)
> return 0;
> ct->when = time(NULL);
> return 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. You'll have to call post_parse_clinic_time_t()
> by hand in your impl function; I'll see if I can extend Clinic so
> converters can emit code after a successful call to the parse function
> but before the call to the impl.
Okay, I attached a patch along these lines to the bugtracker.
However, I have to say that I lost track of what we're actually gaining
with all this. If all we need is a type that can distinguish between a
valid time_t value and a default value, why don't we simply use
PyObject?
In other words, what's the advantage of all the code above over:
static int
PyObject_to_time_t(PyObject *obj, time_t *when)
{
if (obj == NULL || obj == Py_None)
*when = time(NULL);
else if (_PyTime_ObjectToTime_t(obj, when) == -1)
return 0;
return 1;
}
/*[clinic input]
time.gmtime
seconds: object=NULL
/
[...]
static PyObject *
time_gmtime_impl(PyModuleDef *module, PyObject *seconds)
{
PyObject *return_value = NULL;
time_t when;
if(!PyObj_to_time_t(seconds, &when))
return NULL;
[...]
To me this version looks shorter and clearer. Is there really an
advantage in defining the clinic argument as a custom struct rather than
object?
Best,
-Nikolaus
--
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»Time flies like an arrow, fruit flies like a Banana.«
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