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import unittest
from test import test_support
def funcattrs(**kwds):
def decorate(func):
func.__dict__.update(kwds)
return func
return decorate
class MiscDecorators (object):
@staticmethod
def author(name):
def decorate(func):
func.__dict__['author'] = name
return func
return decorate
# -----------------------------------------------
class DbcheckError (Exception):
def __init__(self, exprstr, func, args, kwds):
# A real version of this would set attributes here
Exception.__init__(self, "dbcheck %r failed (func=%s args=%s kwds=%s)" %
(exprstr, func, args, kwds))
def dbcheck(exprstr, globals=None, locals=None):
"Decorator to implement debugging assertions"
def decorate(func):
expr = compile(exprstr, "dbcheck-%s" % func.func_name, "eval")
def check(*args, **kwds):
if not eval(expr, globals, locals):
raise DbcheckError(exprstr, func, args, kwds)
return func(*args, **kwds)
return check
return decorate
# -----------------------------------------------
def countcalls(counts):
"Decorator to count calls to a function"
def decorate(func):
name = func.func_name
counts[name] = 0
def call(*args, **kwds):
counts[name] += 1
return func(*args, **kwds)
# XXX: Would like to say: call.func_name = func.func_name here
# to make nested decorators work in any order, but func_name
# is a readonly attribute
return call
return decorate
# -----------------------------------------------
def memoize(func):
saved = {}
def call(*args):
try:
return saved[args]
except KeyError:
res = func(*args)
saved[args] = res
return res
except TypeError:
# Unhashable argument
return func(*args)
return call
# -----------------------------------------------
class TestDecorators(unittest.TestCase):
def test_single(self):
class C(object):
@staticmethod
def foo(): return 42
self.assertEqual(C.foo(), 42)
self.assertEqual(C().foo(), 42)
def test_staticmethod_function(self):
@staticmethod
def notamethod(x):
return x
self.assertRaises(TypeError, notamethod, 1)
def test_dotted(self):
decorators = MiscDecorators()
@decorators.author('Cleese')
def foo(): return 42
self.assertEqual(foo(), 42)
self.assertEqual(foo.author, 'Cleese')
def test_argforms(self):
# A few tests of argument passing, as we use restricted form
# of expressions for decorators.
def noteargs(*args, **kwds):
def decorate(func):
setattr(func, 'dbval', (args, kwds))
return func
return decorate
args = ( 'Now', 'is', 'the', 'time' )
kwds = dict(one=1, two=2)
@noteargs(*args, **kwds)
def f1(): return 42
self.assertEqual(f1(), 42)
self.assertEqual(f1.dbval, (args, kwds))
@noteargs('terry', 'gilliam', eric='idle', john='cleese')
def f2(): return 84
self.assertEqual(f2(), 84)
self.assertEqual(f2.dbval, (('terry', 'gilliam'),
dict(eric='idle', john='cleese')))
@noteargs(1, 2,)
def f3(): pass
self.assertEqual(f3.dbval, ((1, 2), {}))
def test_dbcheck(self):
@dbcheck('args[1] is not None')
def f(a, b):
return a + b
self.assertEqual(f(1, 2), 3)
self.assertRaises(DbcheckError, f, 1, None)
def test_memoize(self):
# XXX: This doesn't work unless memoize is the last decorator -
# see the comment in countcalls.
counts = {}
@memoize
@countcalls(counts)
def double(x):
return x * 2
self.assertEqual(counts, dict(double=0))
# Only the first call with a given argument bumps the call count:
#
self.assertEqual(double(2), 4)
self.assertEqual(counts['double'], 1)
self.assertEqual(double(2), 4)
self.assertEqual(counts['double'], 1)
self.assertEqual(double(3), 6)
self.assertEqual(counts['double'], 2)
# Unhashable arguments do not get memoized:
#
self.assertEqual(double([10]), [10, 10])
self.assertEqual(counts['double'], 3)
self.assertEqual(double([10]), [10, 10])
self.assertEqual(counts['double'], 4)
def test_errors(self):
# Test syntax restrictions - these are all compile-time errors:
#
for expr in [ "1+2", "x[3]", "(1, 2)" ]:
# Sanity check: is expr is a valid expression by itself?
compile(expr, "testexpr", "exec")
codestr = "@%s\ndef f(): pass" % expr
self.assertRaises(SyntaxError, compile, codestr, "test", "exec")
# Test runtime errors
def unimp(func):
raise NotImplementedError
context = dict(nullval=None, unimp=unimp)
for expr, exc in [ ("undef", NameError),
("nullval", TypeError),
("nullval.attr", AttributeError),
("unimp", NotImplementedError)]:
codestr = "@%s\ndef f(): pass\nassert f() is None" % expr
code = compile(codestr, "test", "exec")
self.assertRaises(exc, eval, code, context)
def test_double(self):
class C(object):
@funcattrs(abc=1, xyz="haha")
@funcattrs(booh=42)
def foo(self): return 42
self.assertEqual(C().foo(), 42)
self.assertEqual(C.foo.abc, 1)
self.assertEqual(C.foo.xyz, "haha")
self.assertEqual(C.foo.booh, 42)
def test_order(self):
# Test that decorators are conceptually applied right-recursively;
# that means bottom-up
def ordercheck(num):
def deco(func):
return lambda: num
return deco
# Should go ordercheck(1)(ordercheck(2)(blah)) which should lead to
# blah() == 1
@ordercheck(1)
@ordercheck(2)
def blah(): pass
self.assertEqual(blah(), 1, "decorators are meant to be applied "
"bottom-up")
def test_main():
test_support.run_unittest(TestDecorators)
if __name__=="__main__":
test_main()
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