import unittest
import weakref
from test.support import check_syntax_error, cpython_only
from test.support import gc_collect
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()
gc_collect() # For PyPy or other GCs.
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
gc_collect() # For PyPy or other GCs.
self.assertIsNone(ref())
def test_multiple_nesting(self):
# Regression test for https://github.com/python/cpython/issues/121863
class MultiplyNested:
def f1(self):
__arg = 1
class D:
def g(self, __arg):
return __arg
return D().g(_MultiplyNested__arg=2)
def f2(self):
__arg = 1
class D:
def g(self, __arg):
return __arg
return D().g
inst = MultiplyNested()
with self.assertRaises(TypeError):
inst.f1()
closure = inst.f2()
with self.assertRaises(TypeError):
closure(_MultiplyNested__arg=2)
if __name__ == '__main__':
unittest.main()
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