cpython/Lib/test/test_coercion.py

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import copy
import sys
import warnings
# Fake a number that implements numeric methods through __coerce__
class CoerceNumber:
def __init__(self, arg):
self.arg = arg
def __repr__(self):
return '<CoerceNumber %s>' % repr(self.arg)
def __coerce__(self, other):
if isinstance(other, CoerceNumber):
return self.arg, other.arg
else:
return (self.arg, other)
# Fake a number that implements numeric ops through methods.
class MethodNumber:
def __init__(self,arg):
self.arg = arg
def __repr__(self):
return '<MethodNumber %s>' % repr(self.arg)
def __add__(self,other):
return self.arg + other
def __radd__(self,other):
return other + self.arg
def __sub__(self,other):
return self.arg - other
def __rsub__(self,other):
return other - self.arg
def __mul__(self,other):
return self.arg * other
def __rmul__(self,other):
return other * self.arg
def __div__(self,other):
return self.arg / other
def __rdiv__(self,other):
return other / self.arg
def __pow__(self,other):
return self.arg ** other
def __rpow__(self,other):
return other ** self.arg
def __mod__(self,other):
return self.arg % other
def __rmod__(self,other):
return other % self.arg
def __cmp__(self, other):
return cmp(self.arg, other)
candidates = [ 2, 4.0, 2L, 2+0j, [1], (2,), None,
MethodNumber(2), CoerceNumber(2)]
infix_binops = [ '+', '-', '*', '/', '**', '%' ]
prefix_binops = [ 'divmod' ]
def format_float(value):
if abs(value) < 0.01:
return '0.0'
else:
return '%.1f' % value
# avoid testing platform fp quirks
def format_result(value):
if isinstance(value, complex):
return '(%s + %sj)' % (format_float(value.real),
format_float(value.imag))
elif isinstance(value, float):
return format_float(value)
return str(value)
def do_infix_binops():
for a in candidates:
for b in candidates:
for op in infix_binops:
print '%s %s %s' % (a, op, b),
try:
x = eval('a %s b' % op)
except:
error = sys.exc_info()[:2]
print '... %s' % error[0]
else:
print '=', format_result(x)
try:
z = copy.copy(a)
except copy.Error:
z = a # assume it has no inplace ops
print '%s %s= %s' % (a, op, b),
try:
exec('z %s= b' % op)
except:
error = sys.exc_info()[:2]
print '... %s' % error[0]
else:
print '=>', format_result(z)
def do_prefix_binops():
for a in candidates:
for b in candidates:
for op in prefix_binops:
print '%s(%s, %s)' % (op, a, b),
try:
x = eval('%s(a, b)' % op)
except:
error = sys.exc_info()[:2]
print '... %s' % error[0]
else:
print '=', format_result(x)
# New-style class version of CoerceNumber
class CoerceTo(object):
def __init__(self, arg):
self.arg = arg
def __coerce__(self, other):
if isinstance(other, CoerceTo):
return self.arg, other.arg
else:
return self.arg, other
def assert_(expr, msg=None):
if not expr:
raise AssertionError, msg
def do_cmptypes():
# Built-in tp_compare slots expect their arguments to have the
# same type, but a user-defined __coerce__ doesn't have to obey.
# SF #980352
evil_coercer = CoerceTo(42)
# Make sure these don't crash any more
assert_(cmp(u'fish', evil_coercer) != 0)
assert_(cmp(slice(1), evil_coercer) != 0)
# ...but that this still works
class WackyComparer(object):
def __cmp__(self, other):
assert_(other == 42, 'expected evil_coercer, got %r' % other)
return 0
assert_(cmp(WackyComparer(), evil_coercer) == 0)
# ...and classic classes too, since that code path is a little different
class ClassicWackyComparer:
def __cmp__(self, other):
assert_(other == 42, 'expected evil_coercer, got %r' % other)
return 0
assert_(cmp(ClassicWackyComparer(), evil_coercer) == 0)
warnings.filterwarnings("ignore",
r'complex divmod\(\), // and % are deprecated',
DeprecationWarning,
r'test.test_coercion$')
do_infix_binops()
do_prefix_binops()
do_cmptypes()