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1"""This module includes tests of the code object representation.
2
3>>> def f(x):
4...     def g(y):
5...         return x + y
6...     return g
7...
8
9>>> dump(f.func_code)
10name: f
11argcount: 1
12names: ()
13varnames: ('x', 'g')
14cellvars: ('x',)
15freevars: ()
16nlocals: 2
17flags: 3
18consts: ('None', '<code object g>')
19
20>>> dump(f(4).func_code)
21name: g
22argcount: 1
23names: ()
24varnames: ('y',)
25cellvars: ()
26freevars: ('x',)
27nlocals: 1
28flags: 19
29consts: ('None',)
30
31>>> def h(x, y):
32...     a = x + y
33...     b = x - y
34...     c = a * b
35...     return c
36...
37>>> dump(h.func_code)
38name: h
39argcount: 2
40names: ()
41varnames: ('x', 'y', 'a', 'b', 'c')
42cellvars: ()
43freevars: ()
44nlocals: 5
45flags: 67
46consts: ('None',)
47
48>>> def attrs(obj):
49...     print obj.attr1
50...     print obj.attr2
51...     print obj.attr3
52
53>>> dump(attrs.func_code)
54name: attrs
55argcount: 1
56names: ('attr1', 'attr2', 'attr3')
57varnames: ('obj',)
58cellvars: ()
59freevars: ()
60nlocals: 1
61flags: 67
62consts: ('None',)
63
64>>> def optimize_away():
65...     'doc string'
66...     'not a docstring'
67...     53
68...     53L
69
70>>> dump(optimize_away.func_code)
71name: optimize_away
72argcount: 0
73names: ()
74varnames: ()
75cellvars: ()
76freevars: ()
77nlocals: 0
78flags: 67
79consts: ("'doc string'", 'None')
80
81"""
82
83import unittest
84import weakref
85from test.test_support import run_doctest, run_unittest, cpython_only
86
87
88def consts(t):
89    """Yield a doctest-safe sequence of object reprs."""
90    for elt in t:
91        r = repr(elt)
92        if r.startswith("<code object"):
93            yield "<code object %s>" % elt.co_name
94        else:
95            yield r
96
97def dump(co):
98    """Print out a text representation of a code object."""
99    for attr in ["name", "argcount", "names", "varnames", "cellvars",
100                 "freevars", "nlocals", "flags"]:
101        print "%s: %s" % (attr, getattr(co, "co_" + attr))
102    print "consts:", tuple(consts(co.co_consts))
103
104
105class CodeTest(unittest.TestCase):
106
107    @cpython_only
108    def test_newempty(self):
109        import _testcapi
110        co = _testcapi.code_newempty("filename", "funcname", 15)
111        self.assertEqual(co.co_filename, "filename")
112        self.assertEqual(co.co_name, "funcname")
113        self.assertEqual(co.co_firstlineno, 15)
114
115
116def isinterned(s):
117    return s is intern(('_' + s + '_')[1:-1])
118
119class CodeConstsTest(unittest.TestCase):
120
121    def find_const(self, consts, value):
122        for v in consts:
123            if v == value:
124                return v
125        self.assertIn(value, consts)  # raises an exception
126        self.fail('Should never be reached')
127
128    def assertIsInterned(self, s):
129        if not isinterned(s):
130            self.fail('String %r is not interned' % (s,))
131
132    def assertIsNotInterned(self, s):
133        if isinterned(s):
134            self.fail('String %r is interned' % (s,))
135
136    @cpython_only
137    def test_interned_string(self):
138        co = compile('res = "str_value"', '?', 'exec')
139        v = self.find_const(co.co_consts, 'str_value')
140        self.assertIsInterned(v)
141
142    @cpython_only
143    def test_interned_string_in_tuple(self):
144        co = compile('res = ("str_value",)', '?', 'exec')
145        v = self.find_const(co.co_consts, ('str_value',))
146        self.assertIsInterned(v[0])
147
148    @cpython_only
149    def test_interned_string_default(self):
150        def f(a='str_value'):
151            return a
152        self.assertIsInterned(f())
153
154    @cpython_only
155    def test_interned_string_with_null(self):
156        co = compile(r'res = "str\0value!"', '?', 'exec')
157        v = self.find_const(co.co_consts, 'str\0value!')
158        self.assertIsNotInterned(v)
159
160
161class CodeWeakRefTest(unittest.TestCase):
162
163    def test_basic(self):
164        # Create a code object in a clean environment so that we know we have
165        # the only reference to it left.
166        namespace = {}
167        exec "def f(): pass" in globals(), namespace
168        f = namespace["f"]
169        del namespace
170
171        self.called = False
172        def callback(code):
173            self.called = True
174
175        # f is now the last reference to the function, and through it, the code
176        # object.  While we hold it, check that we can create a weakref and
177        # deref it.  Then delete it, and check that the callback gets called and
178        # the reference dies.
179        coderef = weakref.ref(f.__code__, callback)
180        self.assertTrue(bool(coderef()))
181        del f
182        self.assertFalse(bool(coderef()))
183        self.assertTrue(self.called)
184
185
186def test_main(verbose=None):
187    from test import test_code
188    run_doctest(test_code, verbose)
189    run_unittest(CodeTest, CodeConstsTest, CodeWeakRefTest)
190
191
192if __name__ == "__main__":
193    test_main()
194