Lib/ctypes/test/test_stringptr.py
import unittest from ctypes import * import _ctypes_test lib = CDLL(_ctypes_test.__file__) class StringPtrTestCase(unittest.TestCase): def test__POINTER_c_char(self): class X(Structure): _fields_ = [("str", POINTER(c_char))] x = X() # NULL pointer access self.assertRaises(ValueError, getattr, x.str, "contents") b = c_buffer("Hello, World") from sys import getrefcount as grc self.assertEqual(grc(b), 2) x.str = b self.assertEqual(grc(b), 3) # POINTER(c_char) and Python string is NOT compatible # POINTER(c_char) and c_buffer() is compatible for i in range(len(b)): self.assertEqual(b[i], x.str[i]) self.assertRaises(TypeError, setattr, x, "str", "Hello, World") def test__c_char_p(self): class X(Structure): _fields_ = [("str", c_char_p)] x = X() # c_char_p and Python string is compatible # c_char_p and c_buffer is NOT compatible self.assertEqual(x.str, None) x.str = "Hello, World" self.assertEqual(x.str, "Hello, World") b = c_buffer("Hello, World") self.assertRaises(TypeError, setattr, x, "str", b) def test_functions(self): strchr = lib.my_strchr strchr.restype = c_char_p # c_char_p and Python string is compatible # c_char_p and c_buffer are now compatible strchr.argtypes = c_char_p, c_char self.assertEqual(strchr("abcdef", "c"), "cdef") self.assertEqual(strchr(c_buffer("abcdef"), "c"), "cdef") # POINTER(c_char) and Python string is NOT compatible # POINTER(c_char) and c_buffer() is compatible strchr.argtypes = POINTER(c_char), c_char buf = c_buffer("abcdef") self.assertEqual(strchr(buf, "c"), "cdef") self.assertEqual(strchr("abcdef", "c"), "cdef") # XXX These calls are dangerous, because the first argument # to strchr is no longer valid after the function returns! # So we must keep a reference to buf separately strchr.restype = POINTER(c_char) buf = c_buffer("abcdef") r = strchr(buf, "c") x = r[0], r[1], r[2], r[3], r[4] self.assertEqual(x, ("c", "d", "e", "f", "\000")) del buf # x1 will NOT be the same as x, usually: x1 = r[0], r[1], r[2], r[3], r[4] if __name__ == '__main__': unittest.main() |