Lib/ctypes/test/test_callbacks.py

import unittest
from ctypes import *
import _ctypes_test

class Callbacks(unittest.TestCase):
    functype = CFUNCTYPE

##    def tearDown(self):
##        import gc
##        gc.collect()

    def callback(self, *args):
        self.got_args = args
        return args[-1]

    def check_type(self, typ, arg):
        PROTO = self.functype.im_func(typ, typ)
        result = PROTO(self.callback)(arg)
        if typ == c_float:
            self.failUnlessAlmostEqual(result, arg, places=5)
        else:
            self.failUnlessEqual(self.got_args, (arg,))
            self.failUnlessEqual(result, arg)

        PROTO = self.functype.im_func(typ, c_byte, typ)
        result = PROTO(self.callback)(-3, arg)
        if typ == c_float:
            self.failUnlessAlmostEqual(result, arg, places=5)
        else:
            self.failUnlessEqual(self.got_args, (-3, arg))
            self.failUnlessEqual(result, arg)

    ################

    def test_byte(self):
        self.check_type(c_byte, 42)
        self.check_type(c_byte, -42)

    def test_ubyte(self):
        self.check_type(c_ubyte, 42)

    def test_short(self):
        self.check_type(c_short, 42)
        self.check_type(c_short, -42)

    def test_ushort(self):
        self.check_type(c_ushort, 42)

    def test_int(self):
        self.check_type(c_int, 42)
        self.check_type(c_int, -42)

    def test_uint(self):
        self.check_type(c_uint, 42)

    def test_long(self):
        self.check_type(c_long, 42)
        self.check_type(c_long, -42)

    def test_ulong(self):
        self.check_type(c_ulong, 42)

    def test_longlong(self):
        self.check_type(c_longlong, 42)
        self.check_type(c_longlong, -42)

    def test_ulonglong(self):
        self.check_type(c_ulonglong, 42)

    def test_float(self):
        # only almost equal: double -> float -> double
        import math
        self.check_type(c_float, math.e)
        self.check_type(c_float, -math.e)

    def test_double(self):
        self.check_type(c_double, 3.14)
        self.check_type(c_double, -3.14)

    def test_char(self):
        self.check_type(c_char, "x")
        self.check_type(c_char, "a")

    # disabled: would now (correctly) raise a RuntimeWarning about
    # a memory leak.  A callback function cannot return a non-integral
    # C type without causing a memory leak.
##    def test_char_p(self):
##        self.check_type(c_char_p, "abc")
##        self.check_type(c_char_p, "def")

    def test_pyobject(self):
        o = ()
        from sys import getrefcount as grc
        for o in (), [], object():
            initial = grc(o)
            # This call leaks a reference to 'o'...
            self.check_type(py_object, o)
            before = grc(o)
            # ...but this call doesn't leak any more.  Where is the refcount?
            self.check_type(py_object, o)
            after = grc(o)
            self.failUnlessEqual((after, o), (before, o))

    def test_unsupported_restype_1(self):
        # Only "fundamental" result types are supported for callback
        # functions, the type must have a non-NULL stgdict->setfunc.
        # POINTER(c_double), for example, is not supported.

        prototype = self.functype.im_func(POINTER(c_double))
        # The type is checked when the prototype is called
        self.assertRaises(TypeError, prototype, lambda: None)

    def test_unsupported_restype_2(self):
        prototype = self.functype.im_func(object)
        self.assertRaises(TypeError, prototype, lambda: None)

try:
    WINFUNCTYPE
except NameError:
    pass
else:
    class StdcallCallbacks(Callbacks):
        functype = WINFUNCTYPE

################################################################

class SampleCallbacksTestCase(unittest.TestCase):

    def test_integrate(self):
        # Derived from some then non-working code, posted by David Foster
        dll = CDLL(_ctypes_test.__file__)

        # The function prototype called by 'integrate': double func(double);
        CALLBACK = CFUNCTYPE(c_double, c_double)

        # The integrate function itself, exposed from the _ctypes_test dll
        integrate = dll.integrate
        integrate.argtypes = (c_double, c_double, CALLBACK, c_long)
        integrate.restype = c_double

        def func(x):
            return x**2

        result = integrate(0.0, 1.0, CALLBACK(func), 10)
        diff = abs(result - 1./3.)

        self.failUnless(diff < 0.01, "%s not less than 0.01" % diff)

################################################################

if __name__ == '__main__':
    unittest.main()