import unittest import weakref from test.support import check_syntax_error, cpython_only class ScopeTests(unittest.TestCase): def testSimpleNesting(self): def make_adder(x): def adder(y): return x + y return adder inc = make_adder(1) plus10 = make_adder(10) self.assertEqual(inc(1), 2) self.assertEqual(plus10(-2), 8) def testExtraNesting(self): def make_adder2(x): def extra(): # check freevars passing through non-use scopes def adder(y): return x + y return adder return extra() inc = make_adder2(1) plus10 = make_adder2(10) self.assertEqual(inc(1), 2) self.assertEqual(plus10(-2), 8) def testSimpleAndRebinding(self): def make_adder3(x): def adder(y): return x + y x = x + 1 # check tracking of assignment to x in defining scope return adder inc = make_adder3(0) plus10 = make_adder3(9) self.assertEqual(inc(1), 2) self.assertEqual(plus10(-2), 8) def testNestingGlobalNoFree(self): def make_adder4(): # XXX add exta level of indirection def nest(): def nest(): def adder(y): return global_x + y # check that plain old globals work return adder return nest() return nest() global_x = 1 adder = make_adder4() self.assertEqual(adder(1), 2) global_x = 10 self.assertEqual(adder(-2), 8) def testNestingThroughClass(self): def make_adder5(x): class Adder: def __call__(self, y): return x + y return Adder() inc = make_adder5(1) plus10 = make_adder5(10) self.assertEqual(inc(1), 2) self.assertEqual(plus10(-2), 8) def testNestingPlusFreeRefToGlobal(self): def make_adder6(x): global global_nest_x def adder(y): return global_nest_x + y global_nest_x = x return adder inc = make_adder6(1) plus10 = make_adder6(10) self.assertEqual(inc(1), 11) # there's only one global self.assertEqual(plus10(-2), 8) def testNearestEnclosingScope(self): def f(x): def g(y): x = 42 # check that this masks binding in f() def h(z): return x + z return h return g(2) test_func = f(10) self.assertEqual(test_func(5), 47) def testMixedFreevarsAndCellvars(self): def identity(x): return x def f(x, y, z): def g(a, b, c): a = a + x # 3 def h(): # z * (4 + 9) # 3 * 13 return identity(z * (b + y)) y = c + z # 9 return h return g g = f(1, 2, 3) h = g(2, 4, 6) self.assertEqual(h(), 39) def testFreeVarInMethod(self): def test(): method_and_var = "var" class Test: def method_and_var(self): return "method" def test(self): return method_and_var def actual_global(self): return str("global") def str(self): return str(self) return Test() t = test() self.assertEqual(t.test(), "var") self.assertEqual(t.method_and_var(), "method") self.assertEqual(t.actual_global(), "global") method_and_var = "var" class Test: # this class is not nested, so the rules are different def method_and_var(self): return "method" def test(self): return method_and_var def actual_global(self): return str("global") def str(self): return str(self) t = Test() self.assertEqual(t.test(), "var") self.assertEqual(t.method_and_var(), "method") self.assertEqual(t.actual_global(), "global") def testCellIsKwonlyArg(self): # Issue 1409: Initialisation of a cell value, # when it comes from a keyword-only parameter def foo(*, a=17): def bar(): return a + 5 return bar() + 3 self.assertEqual(foo(a=42), 50) self.assertEqual(foo(), 25) def testCellIsArgAndEscapes(self): # We need to be sure that a cell passed in as an arg still # gets wrapped in a new cell if the arg escapes into an # inner function (closure). def external(): value = 42 def inner(): return value cell, = inner.__closure__ return cell cell_ext = external() def spam(arg): def eggs(): return arg return eggs eggs = spam(cell_ext) cell_closure, = eggs.__closure__ cell_eggs = eggs() self.assertIs(cell_eggs, cell_ext) self.assertIsNot(cell_eggs, cell_closure) def testCellIsLocalAndEscapes(self): # We need to be sure that a cell bound to a local still # gets wrapped in a new cell if the local escapes into an # inner function (closure). def external(): value = 42 def inner(): return value cell, = inner.__closure__ return cell cell_ext = external() def spam(arg): cell = arg def eggs(): return cell return eggs eggs = spam(cell_ext) cell_closure, = eggs.__closure__ cell_eggs = eggs() self.assertIs(cell_eggs, cell_ext) self.assertIsNot(cell_eggs, cell_closure) def testRecursion(self): def f(x): def fact(n): if n == 0: return 1 else: return n * fact(n - 1) if x >= 0: return fact(x) else: raise ValueError("x must be >= 0") self.assertEqual(f(6), 720) def testUnoptimizedNamespaces(self): check_syntax_error(self, """if 1: def unoptimized_clash1(strip): def f(s): from sys import * return getrefcount(s) # ambiguity: free or local return f """) check_syntax_error(self, """if 1: def unoptimized_clash2(): from sys import * def f(s): return getrefcount(s) # ambiguity: global or local return f """) check_syntax_error(self, """if 1: def unoptimized_clash2(): from sys import * def g(): def f(s): return getrefcount(s) # ambiguity: global or local return f """) check_syntax_error(self, """if 1: def f(): def g(): from sys import * return getrefcount # global or local? """) def testLambdas(self): f1 = lambda x: lambda y: x + y inc = f1(1) plus10 = f1(10) self.assertEqual(inc(1), 2) self.assertEqual(plus10(5), 15) f2 = lambda x: (lambda : lambda y: x + y)() inc = f2(1) plus10 = f2(10) self.assertEqual(inc(1), 2) self.assertEqual(plus10(5), 15) f3 = lambda x: lambda y: global_x + y global_x = 1 inc = f3(None) self.assertEqual(inc(2), 3) f8 = lambda x, y, z: lambda a, b, c: lambda : z * (b + y) g = f8(1, 2, 3) h = g(2, 4, 6) self.assertEqual(h(), 18) def testUnboundLocal(self): def errorInOuter(): print(y) def inner(): return y y = 1 def errorInInner(): def inner(): return y inner() y = 1 self.assertRaises(UnboundLocalError, errorInOuter) self.assertRaises(NameError, errorInInner) def testUnboundLocal_AfterDel(self): # #4617: It is now legal to delete a cell variable. # The following functions must obviously compile, # and give the correct error when accessing the deleted name. def errorInOuter(): y = 1 del y print(y) def inner(): return y def errorInInner(): def inner(): return y y = 1 del y inner() self.assertRaises(UnboundLocalError, errorInOuter) self.assertRaises(NameError, errorInInner) def testUnboundLocal_AugAssign(self): # test for bug #1501934: incorrect LOAD/STORE_GLOBAL generation exec("""if 1: global_x = 1 def f(): global_x += 1 try: f() except UnboundLocalError: pass else: fail('scope of global_x not correctly determined') """, {'fail': self.fail}) def testComplexDefinitions(self): def makeReturner(*lst): def returner(): return lst return returner self.assertEqual(makeReturner(1,2,3)(), (1,2,3)) def makeReturner2(**kwargs): def returner(): return kwargs return returner self.assertEqual(makeReturner2(a=11)()['a'], 11) def testScopeOfGlobalStmt(self): # Examples posted by Samuele Pedroni to python-dev on 3/1/2001 exec("""if 1: # I x = 7 def f(): x = 1 def g(): global x def i(): def h(): return x return h() return i() return g() self.assertEqual(f(), 7) self.assertEqual(x, 7) # II x = 7 def f(): x = 1 def g(): x = 2 def i(): def h(): return x return h() return i() return g() self.assertEqual(f(), 2) self.assertEqual(x, 7) # III x = 7 def f(): x = 1 def g(): global x x = 2 def i(): def h(): return x return h() return i() return g() self.assertEqual(f(), 2) self.assertEqual(x, 2) # IV x = 7 def f(): x = 3 def g(): global x x = 2 def i(): def h(): return x return h() return i() return g() self.assertEqual(f(), 2) self.assertEqual(x, 2) # XXX what about global statements in class blocks? # do they affect methods? x = 12 class Global: global x x = 13 def set(self, val): x = val def get(self): return x g = Global() self.assertEqual(g.get(), 13) g.set(15) self.assertEqual(g.get(), 13) """) def testLeaks(self): class Foo: count = 0 def __init__(self): Foo.count += 1 def __del__(self): Foo.count -= 1 def f1(): x = Foo() def f2(): return x f2() for i in range(100): f1() self.assertEqual(Foo.count, 0) def testClassAndGlobal(self): exec("""if 1: def test(x): class Foo: global x def __call__(self, y): return x + y return Foo() x = 0 self.assertEqual(test(6)(2), 8) x = -1 self.assertEqual(test(3)(2), 5) looked_up_by_load_name = False class X: # Implicit globals inside classes are be looked up by LOAD_NAME, not # LOAD_GLOBAL. locals()['looked_up_by_load_name'] = True passed = looked_up_by_load_name self.assertTrue(X.passed) """) def testLocalsFunction(self): def f(x): def g(y): def h(z): return y + z w = x + y y += 3 return locals() return g d = f(2)(4) self.assertIn('h', d) del d['h'] self.assertEqual(d, {'x': 2, 'y': 7, 'w': 6}) def testLocalsClass(self): # This test verifies that calling locals() does not pollute # the local namespace of the class with free variables. Old # versions of Python had a bug, where a free variable being # passed through a class namespace would be inserted into # locals() by locals() or exec or a trace function. # # The real bug lies in frame code that copies variables # between fast locals and the locals dict, e.g. when executing # a trace function. def f(x): class C: x = 12 def m(self): return x locals() return C self.assertEqual(f(1).x, 12) def f(x): class C: y = x def m(self): return x z = list(locals()) return C varnames = f(1).z self.assertNotIn("x", varnames) self.assertIn("y", varnames) @cpython_only def testLocalsClass_WithTrace(self): # Issue23728: after the trace function returns, the locals() # dictionary is used to update all variables, this used to # include free variables. But in class statements, free # variables are not inserted... import sys self.addCleanup(sys.settrace, sys.gettrace()) sys.settrace(lambda a,b,c:None) x = 12 class C: def f(self): return x self.assertEqual(x, 12) # Used to raise UnboundLocalError def testBoundAndFree(self): # var is bound and free in class def f(x): class C: def m(self): return x a = x return C inst = f(3)() self.assertEqual(inst.a, inst.m()) @cpython_only def testInteractionWithTraceFunc(self): import sys def tracer(a,b,c): return tracer def adaptgetter(name, klass, getter): kind, des = getter if kind == 1: # AV happens when stepping from this line to next if des == "": des = "_%s__%s" % (klass.__name__, name) return lambda obj: getattr(obj, des) class TestClass: pass self.addCleanup(sys.settrace, sys.gettrace()) sys.settrace(tracer) adaptgetter("foo", TestClass, (1, "")) sys.settrace(None) self.assertRaises(TypeError, sys.settrace) def testEvalExecFreeVars(self): def f(x): return lambda: x + 1 g = f(3) self.assertRaises(TypeError, eval, g.__code__) try: exec(g.__code__, {}) except TypeError: pass else: self.fail("exec should have failed, because code contained free vars") def testListCompLocalVars(self): try: print(bad) except NameError: pass else: print("bad should not be defined") def x(): [bad for s in 'a b' for bad in s.split()] x() try: print(bad) except NameError: pass def testEvalFreeVars(self): def f(x): def g(): x eval("x + 1") return g f(4)() def testFreeingCell(self): # Test what happens when a finalizer accesses # the cell where the object was stored. class Special: def __del__(self): nestedcell_get() def testNonLocalFunction(self): def f(x): def inc(): nonlocal x x += 1 return x def dec(): nonlocal x x -= 1 return x return inc, dec inc, dec = f(0) self.assertEqual(inc(), 1) self.assertEqual(inc(), 2) self.assertEqual(dec(), 1) self.assertEqual(dec(), 0) def testNonLocalMethod(self): def f(x): class c: def inc(self): nonlocal x x += 1 return x def dec(self): nonlocal x x -= 1 return x return c() c = f(0) self.assertEqual(c.inc(), 1) self.assertEqual(c.inc(), 2) self.assertEqual(c.dec(), 1) self.assertEqual(c.dec(), 0) def testGlobalInParallelNestedFunctions(self): # A symbol table bug leaked the global statement from one # function to other nested functions in the same block. # This test verifies that a global statement in the first # function does not affect the second function. local_ns = {} global_ns = {} exec("""if 1: def f(): y = 1 def g(): global y return y def h(): return y + 1 return g, h y = 9 g, h = f() result9 = g() result2 = h() """, local_ns, global_ns) self.assertEqual(2, global_ns["result2"]) self.assertEqual(9, global_ns["result9"]) def testNonLocalClass(self): def f(x): class c: nonlocal x x += 1 def get(self): return x return c() c = f(0) self.assertEqual(c.get(), 1) self.assertNotIn("x", c.__class__.__dict__) def testNonLocalGenerator(self): def f(x): def g(y): nonlocal x for i in range(y): x += 1 yield x return g g = f(0) self.assertEqual(list(g(5)), [1, 2, 3, 4, 5]) def testNestedNonLocal(self): def f(x): def g(): nonlocal x x -= 2 def h(): nonlocal x x += 4 return x return h return g g = f(1) h = g() self.assertEqual(h(), 3) def testTopIsNotSignificant(self): # See #9997. def top(a): pass def b(): global a def testClassNamespaceOverridesClosure(self): # See #17853. x = 42 class X: locals()["x"] = 43 y = x self.assertEqual(X.y, 43) class X: locals()["x"] = 43 del x self.assertFalse(hasattr(X, "x")) self.assertEqual(x, 42) @cpython_only def testCellLeak(self): # Issue 17927. # # The issue was that if self was part of a cycle involving the # frame of a method call, *and* the method contained a nested # function referencing self, thereby forcing 'self' into a # cell, setting self to None would not be enough to break the # frame -- the frame had another reference to the instance, # which could not be cleared by the code running in the frame # (though it will be cleared when the frame is collected). # Without the lambda, setting self to None is enough to break # the cycle. class Tester: def dig(self): if 0: lambda: self try: 1/0 except Exception as exc: self.exc = exc self = None # Break the cycle tester = Tester() tester.dig() ref = weakref.ref(tester) del tester self.assertIsNone(ref()) if __name__ == '__main__': unittest.main()