Jim Bosch wrote:
> On 03/14/2013 06:12 PM, Neal Becker wrote:
>> I'm expecting a numpy.random.RandomState object to be passed to me. I want
>> to
>> check it is. The best I could think of is below. Anything more
>> boost::python- ish to do this task?
>>
>> static object rs_obj;
>>
>> template<typename out_type=uint32_t>
>> struct engine {
>> typedef out_type result_type;
>> bp::object rs; // RandomState object
>>
>> void verify (object const& o) {
>> if (!PyObject_IsInstance(o.ptr(), rs_obj.ptr()))
>> throw std::runtime_error ("engine: expected RandomState");
>> }
>>
>> engine (bp::object const& _rs) : rs (_rs) { verify (_rs); }
>> ...
>>
>> BOOST_PYTHON_MODULE...
>>
>> object mod = object (handle<> ((PyImport_ImportModule("numpy.random"))));
>> rs_obj = mod.attr("RandomState");
>>
>
> I believe you can replace the penultimate line with:
>
> bp::object mod = bp::import("numpy.random");
>
> But I can't think of any ways to Boost.Python-ize the rest; there really
> should be an "isinstance" wrapper in Boost.Python, but there isn't. You may
> also want to be a little careful with the return value of PyObject_IsInstance
> - I believe that it's psosible for it to raise an exception instead of simply
> returning 0, and in that case you'd want to use bp::throw_error_already_set()
> to propagate the exception to Python.
>
>
> Jim
Thanks, that seems to work, and looks ever so much prettier.
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