def test_automatic_promotions():
class A: pass
class B(A): pass
a, b = A(), B()
assert_allsame(promote(a, b), (a, b))
assert_allsame(promote(a, a), (a, a))
assert promote_type(A, B) is A
assert promote_type(B, A) is A
def test_custom_promotions(T1, T2):
a, b = T1(1), T2(2)
# Prepare conversions
set_conversion(T2, T1, lambda x: T1(x.data))
set_promotion_rule(T1, T2, T1)
@set_promotion(T1, int, restype=int)
@set_promotion(T2, int, restype=int)
def promote_to_int(x, y):
return convert(x.data, int), y
# Create examples and test
assert_allsame(promote(a, b), (a, T1(2)))
assert_allsame(promote(a, 2), (1, 2))
assert_allsame(promote(a, b, 3), (1, 2, 3))
assert_allsame(promote(3, b, a), (3, 2, 1))
def test_failed_promotions():
with pytest.raises(TypeError):
promote("42", 42)
with pytest.raises(RuntimeError):
set_promotion_rule(float, int, int)
with pytest.raises(RuntimeError):
set_promotion_rule(int, float, int)
with pytest.raises(RuntimeError):
set_promotion(int, float, function=int)
with pytest.raises(RuntimeError):
set_promotion(float, int, function=int)
with pytest.raises(RuntimeError):
set_promotion_rule(str, str, str)
with pytest.raises(RuntimeError):
set_promotion(str, str, function=str)
def dtype(values):
'''Return the dtype for a group of values'''
if not values:
raise TypeError('trying to find the type of an empty list')
values = iter(values)
value = next(values)
tt = type(value)
for v in values:
if not isinstance(v, tt):
try:
value, v = promote(value, v)
tt = type(value)
except TypeError:
tt = commonbase(tt, type(v))
return tt
def test_successfull_promotions_of_base_types():
assert_allsame(promote(1, 2), (1, 2))
assert_allsame(promote(1.0, 2.0), (1.0, 2.0))
assert_allsame(promote(True, 2), (1, 2))
assert_allsame(promote(2, True), (2, 1))
assert_allsame(promote(True, 2, 3.0), (1.0, 2.0, 3.0))