Why does python have to generate the full range to test if float in range?

Question

This is really fast:

1 in range(100000000000000)

This is really slow:

1.5 in range(100000000000000)

Why does the full range have to be generated to know that 1.5 isn't in range(X) when step has to be an integer?

Answer 1

If we check the source code:

The contains function:

range_contains(rangeobject *r, PyObject *ob)
{
    if (PyLong_CheckExact(ob) || PyBool_Check(ob))
        return range_contains_long(r, ob);

    return (int)_PySequence_IterSearch((PyObject*)r, ob,
                                   PY_ITERSEARCH_CONTAINS);
}

It appears to check if it will use an integer or boolean method to check, and if not it uses the PY_ITERSEARCH_CONTAINS.