On 2008-05-07 18:28, Rasmus Andersson wrote:
On 7 maj 2008, at 17.46, M.-A. Lemburg wrote:
On 2008-05-07 17:27, Hrvoje Niksic wrote:
I miss a function able to convert the string representation of a Python primitive number (int, long, float, complex) to an actual number, basically the reverse of repr for numbers. <snip> Would anyone else find this kind of function useful?
Yes.
Perhaps as PyNumber_FromString() ?!
I rarely wrap primitives in objects, as this increases both memory usage, complexity and overhead. (However, sometimes you _might_ need to, but I can't come up with a scenario)
So, in most cases this would probably happen:
PyObject *num = PyNumber_FromString(num_s); if(!PyLong_Check(num)) { // Error... } else { self->event_id = PyLong_AsLongLong(num); }
Not really. The point of the PyNumber_* API is to work on numbers without actually caring or knowing the specific number types (Include/abstract.h).
You'd only do the final conversion to a specific number type at the very end of the calculation using e.g. PyNumber_Int().
In some cases, not even that, since all you're interested in is converting some object to a number object and then passing that to e.g. marshal.
And you lose, because this would be simpler:
self->event_id = strtoll(PyString_AsString(num_s), (char *)NULL, 10); if(errno == EINVAL) { // Error... }
Meaning, you rarely need to take input which can be any kind of number manifested as a string and return it as any number manifested as a native number. (The examples above indicate the output type is known (signed 64bit integer))
Could you maybe give a real-world scenario where this would be needed? Where neither the input not the output number type is known.
Parsing numeric data and converting it to some other format.
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