AttributeError with assertRaises

test_attribute_error_w_variables and test_attribute_error_w_functions show that variables and functions in a module are attributes of the module.

Is a class in a module also an attribute of the module?

preview

I have these tests by the end of the chapter

 1import src.attribute_error
 2
 3
 4def test_attribute_error_w_variables():
 5    src.attribute_error.variable_00
 6    src.attribute_error.variable_01
 7    src.attribute_error.variable_02
 8    src.attribute_error.variable_03
 9    src.attribute_error.variable_04
10    src.attribute_error.variable_05
11    src.attribute_error.variable_06
12    src.attribute_error.variable_07
13    src.attribute_error.variable_08
14    src.attribute_error.variable_09
15
16
17def test_attribute_error_w_functions():
18    src.attribute_error.function_00()
19    src.attribute_error.function_01()
20    src.attribute_error.function_02()
21    src.attribute_error.function_03()
22    src.attribute_error.function_04()
23    src.attribute_error.function_05()
24    src.attribute_error.function_06()
25    src.attribute_error.function_07()
26    src.attribute_error.function_08()
27    src.attribute_error.function_09()
28
29
30def test_attribute_error_w_class_attributes():
31    src.attribute_error.AClass.attribute_00
32    src.attribute_error.AClass().attribute_01
33    src.attribute_error.AClass.attribute_02
34    src.attribute_error.AClass().attribute_03
35    src.attribute_error.AClass.attribute_04
36    src.attribute_error.AClass().attribute_05
37    src.attribute_error.AClass().attribute_06
38    src.attribute_error.AClass.attribute_07
39    src.attribute_error.AClass.attribute_08
40    src.attribute_error.AClass().attribute_09
41
42
43def test_attribute_error_w_class_methods():
44    src.attribute_error.AClass().method_00()
45    src.attribute_error.AClass().method_01()
46    src.attribute_error.AClass().method_02()
47    src.attribute_error.AClass().method_03()
48    src.attribute_error.AClass().method_04()
49    src.attribute_error.AClass().method_05()
50    src.attribute_error.AClass().method_06()
51    src.attribute_error.AClass().method_07()
52    src.attribute_error.AClass().method_08()
53    src.attribute_error.AClass().method_09()
54
55
56# Exceptions seen
57# AssertionError
58# ModuleNotFoundError
59# AttributeError
60# NameError
61# TypeError
62# SyntaxError

open the project

test_attribute_error_w_class_attributes

RED: make it fail

  • I go back to the terminal where the tests are running

  • I add a test for class attributes to test_attribute_error.py

    17def test_attribute_error_w_functions():
18    src.attribute_error.function_00()
19    src.attribute_error.function_01()
20    src.attribute_error.function_02()
21    src.attribute_error.function_03()
22    src.attribute_error.function_04()
23    src.attribute_error.function_05()
24    src.attribute_error.function_06()
25    src.attribute_error.function_07()
26    src.attribute_error.function_08()
27    src.attribute_error.function_09()
28
29
30def test_attribute_error_w_class_attributes():
31    src.attribute_error.AClass.attribute_00
32
33
34# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: module 'src.attribute_error'
                has no attribute 'AClass'

GREEN: make it pass

  • I open attribute_error.py

  • I add a function to attribute_error.py

    22def function_09(): return function_08()
23
24
25def AClass(): return function_09()

    the terminal is my friend, and shows AttributeError

    AttributeError: 'function' object
                has no attribute 'attribute_00'

  • I add a variable for attribute_00 to the function

    25# def AClass(): return function_09()
26def AClass():
27
28    attribute_00 = function_09()
29    return function_09()

    the terminal still shows the same Exception because I cannot get to a variable inside a function from outside the function. The variable is only used inside the function when it runs.

  • I change AClass from a function to a class

    25# def AClass(): return function_09()
26# def AClass():
27class AClass(object):
28
29    attribute_00 = function_09()
30    return function_09()

    the terminal is my friend, and shows SyntaxError

    E    return function_09()
E    ^^^^^^^^^^^^^^^^^^^^
E  SyntaxError: 'return' outside function

    because I cannot use a return statement outside a function.

  • I add SyntaxError to the list of Exceptions seen in test_attribute_error.py

    34# Exceptions seen
35# AssertionError
36# ModuleNotFoundError
37# AttributeError
38# NameError
39# TypeError
40# SyntaxError

  • I comment out the return statement from AClass in attribute_error.py

    25# def AClass(): return function_09()
26# def AClass():
27class AClass(object):
28
29    attribute_00 = function_09()
30    # return function_09()

    • the test passes because attribute_00 is now an attribute/property of the AClass class

    • AClass is an attribute of the attribute_error.py module in the src folder

    • I can use attribute_00 from outside the file with src.attribute_error.AClass.attribute_00 or src.attribute_error.AClass().attribute_00

      src.attribute_error.AClass.attribute_00
src.attribute_error.AClass().attribute_00
src
└── attribute_error.py
    └── class AClass(object):
        └── attribute_00 = function_09()

REFACTOR: make it better

  • I remove the commented lines

    22def function_09(): return function_08()
23
24
25class AClass(object):
26
27    attribute_00 = function_09()

  • I add a line for src.attribute_error.AClass().attribute_01 to test_attribute_error.py

    30def test_attribute_error_w_class_attributes():
31    src.attribute_error.AClass.attribute_00
32    src.attribute_error.AClass().attribute_01
33
34
35# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'attribute_01'.
                Did you mean: 'attribute_00'?

  • I add attribute_01 to the class definition in attribute_error.py

    25class AClass(object):
26
27    attribute_00 = function_09()
28    attribute_01 = attribute_00

    • the test passes because in this case it does not matter if I use the class (AClass) or an instance of the class (AClass()).

    • attribute_01 is now an attribute of AClass in attribute_error.py in the src folder, and I can use it from outside the file with src.attribute_error.AClass.attribute_01 or src.attribute_error.AClass().attribute_01

      src.attribute_error.AClass.attribute_01
src.attribute_error.AClass().attribute_01
src
└── attribute_error.py
    └── class AClass(object):
        └── attribute_01 = attribute_00

  • I add a line for src.attribute_error.AClass.attribute_02 to test_attribute_error.py

    30def test_attribute_error_w_class_attributes():
31    src.attribute_error.AClass.attribute_00
32    src.attribute_error.AClass().attribute_01
33    src.attribute_error.AClass.attribute_02
34
35
36# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'attribute_02'.
                Did you mean: 'attribute_00'?

  • I add attribute_02 to the class definition in attribute_error.py

    25class AClass(object):
26
27    attribute_00 = function_09()
28    attribute_01 = attribute_00
29    attribute_02 = attribute_01

    the test passes because attribute_02 is now an attribute of AClass in attribute_error.py in the src folder, and I can use it from outside the file with src.attribute_error.AClass.attribute_02 or src.attribute_error.AClass().attribute_02

    src.attribute_error.AClass.attribute_02
src.attribute_error.AClass().attribute_02
src
└── attribute_error.py
    └── class AClass(object):
        └── attribute_02 = attribute_01

  • I add a line for src.attribute_error.AClass().attribute_03 to test_attribute_error.py

    30def test_attribute_error_w_class_attributes():
31    src.attribute_error.AClass.attribute_00
32    src.attribute_error.AClass().attribute_01
33    src.attribute_error.AClass.attribute_02
34    src.attribute_error.AClass().attribute_03
35
36
37# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'attribute_03'.
                Did you mean: 'attribute_00'?

  • I add attribute_03 to the class definition in attribute_error.py

    25class AClass(object):
26
27    attribute_00 = function_09()
28    attribute_01 = attribute_00
29    attribute_02 = attribute_01
30    attribute_03 = attribute_02

    the test passes because attribute_03 is now an attribute of AClass in attribute_error.py in the src folder, and I can use it from outside the file with src.attribute_error.AClass.attribute_03 or src.attribute_error.AClass().attribute_03

    src.attribute_error.AClass.attribute_03
src.attribute_error.AClass().attribute_03
src
└── attribute_error.py
    └── class AClass(object):
        └── attribute_03 = attribute_02

  • I add a line for src.attribute_error.AClass.attribute_04 to test_attribute_error.py

    30def test_attribute_error_w_class_attributes():
31    src.attribute_error.AClass.attribute_00
32    src.attribute_error.AClass().attribute_01
33    src.attribute_error.AClass.attribute_02
34    src.attribute_error.AClass().attribute_03
35    src.attribute_error.AClass.attribute_04
36
37
38# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'attribute_04'.
                Did you mean: 'attribute_00'?

  • I add attribute_04 to the class definition in attribute_error.py

    25class AClass(object):
26
27    attribute_00 = function_09()
28    attribute_01 = attribute_00
29    attribute_02 = attribute_01
30    attribute_03 = attribute_02
31    attribute_04 = attribute_03

    the test passes because attribute_04 is now an attribute of AClass in attribute_error.py in the src folder, and I can use it from outside the file with src.attribute_error.AClass.attribute_04 or src.attribute_error.AClass().attribute_04

    src.attribute_error.AClass.attribute_04
src.attribute_error.AClass().attribute_04
src
└── attribute_error.py
    └── class AClass(object):
        └── attribute_04 = attribute_03

  • I add a line for src.attribute_error.AClass().attribute_05 to test_attribute_error.py

    30def test_attribute_error_w_class_attributes():
31    src.attribute_error.AClass.attribute_00
32    src.attribute_error.AClass().attribute_01
33    src.attribute_error.AClass.attribute_02
34    src.attribute_error.AClass().attribute_03
35    src.attribute_error.AClass.attribute_04
36    src.attribute_error.AClass().attribute_05
37
38
39# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'attribute_05'.
                Did you mean: 'attribute_00'?

  • I add attribute_05 to the class definition in attribute_error.py

    25class AClass(object):
26
27    attribute_00 = function_09()
28    attribute_01 = attribute_00
29    attribute_02 = attribute_01
30    attribute_03 = attribute_02
31    attribute_04 = attribute_03
32    attribute_05 = attribute_04

    the test passes because attribute_05 is now an attribute of AClass in attribute_error.py in the src folder, and I can use it from outside the file with src.attribute_error.AClass.attribute_05 or src.attribute_error.AClass().attribute_05

    src.attribute_error.AClass.attribute_05
src.attribute_error.AClass().attribute_05
src
└── attribute_error.py
    └── class AClass(object):
        └── attribute_05 = attribute_04

  • I add a line for src.attribute_error.AClass().attribute_06 to test_attribute_error.py

    30def test_attribute_error_w_class_attributes():
31    src.attribute_error.AClass.attribute_00
32    src.attribute_error.AClass().attribute_01
33    src.attribute_error.AClass.attribute_02
34    src.attribute_error.AClass().attribute_03
35    src.attribute_error.AClass.attribute_04
36    src.attribute_error.AClass().attribute_05
37    src.attribute_error.AClass().attribute_06
38
39
40# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'attribute_06'.
                Did you mean: 'attribute_00'?

  • I add attribute_06 to the class definition in attribute_error.py

    25class AClass(object):
26
27    attribute_00 = function_09()
28    attribute_01 = attribute_00
29    attribute_02 = attribute_01
30    attribute_03 = attribute_02
31    attribute_04 = attribute_03
32    attribute_05 = attribute_04
33    attribute_06 = attribute_05

    the test passes because attribute_06 is now an attribute of AClass in attribute_error.py in the src folder, and I can use it from outside the file with src.attribute_error.AClass.attribute_06 or src.attribute_error.AClass().attribute_06

    src.attribute_error.AClass.attribute_06
src.attribute_error.AClass().attribute_06
src
└── attribute_error.py
    └── class AClass(object):
        └── attribute_06 = attribute_05

  • I add a line for src.attribute_error.AClass.attribute_07 to test_attribute_error.py

    30def test_attribute_error_w_class_attributes():
31    src.attribute_error.AClass.attribute_00
32    src.attribute_error.AClass().attribute_01
33    src.attribute_error.AClass.attribute_02
34    src.attribute_error.AClass().attribute_03
35    src.attribute_error.AClass.attribute_04
36    src.attribute_error.AClass().attribute_05
37    src.attribute_error.AClass().attribute_06
38    src.attribute_error.AClass.attribute_07
39
40
41# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'attribute_07'.
                Did you mean: 'attribute_00'?

  • I add attribute_07 to the class definition in attribute_error.py

    25class AClass(object):
26
27    attribute_00 = function_09()
28    attribute_01 = attribute_00
29    attribute_02 = attribute_01
30    attribute_03 = attribute_02
31    attribute_04 = attribute_03
32    attribute_05 = attribute_04
33    attribute_06 = attribute_05
34    attribute_07 = attribute_06

    the test passes because attribute_07 is now an attribute of AClass in attribute_error.py in the src folder, and I can use it from outside the file with src.attribute_error.AClass.attribute_07 or src.attribute_error.AClass().attribute_07

    src.attribute_error.AClass.attribute_07
src.attribute_error.AClass().attribute_07
src
└── attribute_error.py
    └── class AClass(object):
        └── attribute_07 = attribute_06

  • I add a line for src.attribute_error.AClass.attribute_08 to test_attribute_error.py

    30def test_attribute_error_w_class_attributes():
31    src.attribute_error.AClass.attribute_00
32    src.attribute_error.AClass().attribute_01
33    src.attribute_error.AClass.attribute_02
34    src.attribute_error.AClass().attribute_03
35    src.attribute_error.AClass.attribute_04
36    src.attribute_error.AClass().attribute_05
37    src.attribute_error.AClass().attribute_06
38    src.attribute_error.AClass.attribute_07
39    src.attribute_error.AClass.attribute_08
40
41
42# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'attribute_08'.
                Did you mean: 'attribute_00'?

  • I add attribute_08 to the class definition in attribute_error.py

    25class AClass(object):
26
27    attribute_00 = function_09()
28    attribute_01 = attribute_00
29    attribute_02 = attribute_01
30    attribute_03 = attribute_02
31    attribute_04 = attribute_03
32    attribute_05 = attribute_04
33    attribute_06 = attribute_05
34    attribute_07 = attribute_06
35    attribute_08 = attribute_07

    the test passes because attribute_08 is now an attribute of AClass in attribute_error.py in the src folder, and I can use it from outside the file with src.attribute_error.AClass.attribute_08 or src.attribute_error.AClass().attribute_08

    src.attribute_error.AClass.attribute_08
src.attribute_error.AClass().attribute_08
src
└── attribute_error.py
    └── class AClass(object):
        └── attribute_08 = attribute_07

  • I add a line for src.attribute_error.AClass().attribute_09 to test_attribute_error.py

    30def test_attribute_error_w_class_attributes():
31    src.attribute_error.AClass.attribute_00
32    src.attribute_error.AClass().attribute_01
33    src.attribute_error.AClass.attribute_02
34    src.attribute_error.AClass().attribute_03
35    src.attribute_error.AClass.attribute_04
36    src.attribute_error.AClass().attribute_05
37    src.attribute_error.AClass().attribute_06
38    src.attribute_error.AClass.attribute_07
39    src.attribute_error.AClass.attribute_08
40    src.attribute_error.AClass().attribute_09
41
42
43# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'attribute_09'.
                Did you mean: 'attribute_00'?

  • I add attribute_09 to the class definition in attribute_error.py

    25class AClass(object):
26
27    attribute_00 = function_09()
28    attribute_01 = attribute_00
29    attribute_02 = attribute_01
30    attribute_03 = attribute_02
31    attribute_04 = attribute_03
32    attribute_05 = attribute_04
33    attribute_06 = attribute_05
34    attribute_07 = attribute_06
35    attribute_08 = attribute_07
36    attribute_09 = attribute_08

    the test passes because attribute_09 is now an attribute of AClass in attribute_error.py in the src folder, and I can use it from outside the file with src.attribute_error.AClass.attribute_09 or src.attribute_error.AClass().attribute_09

    src.attribute_error.AClass.attribute_09
src.attribute_error.AClass().attribute_09
src
└── attribute_error.py
    └── class AClass(object):
        └── attribute_09 = attribute_08

  • I add a git commit message in the other terminal

    git commit -am \
'add test_attribute_error_w_class_attributes'

  • A variable in a class is an attribute of the class

  • A class in a module is an attribute of the module

  • A function in a module is an attribute of the module

  • A variable in a module is an attribute of the module

test_attribute_error_w_class_methods

The tests show that variables, functions and classes in a module are attributes of the module, and variables in a class are attributes of the class.

Methods of a class are also attributes of the class.

RED: make it fail

  • I go back to the terminal where the tests are running

  • I add a test for methods to test_attribute_error.py

    38        src.attribute_error.AClass().attribute_06
39        src.attribute_error.AClass().attribute_07
40        src.attribute_error.AClass().attribute_08
41        src.attribute_error.AClass().attribute_09
42
43    def test_attribute_error_w_class_methods(self):
44        src.attribute_error.AClass.method_00()
45
46
47# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'method_00'

GREEN: make it pass

  • I add the name to AClass and point it to None, in attribute_error.py

    25class AClass(object):
26
27    attribute_00 = None
28    attribute_01 = None
29    attribute_02 = None
30    attribute_03 = None
31    attribute_04 = None
32    attribute_05 = None
33    attribute_06 = None
34    attribute_07 = None
35    attribute_08 = None
36    attribute_09 = None
37
38    method_00 = None

    the terminal is my friend, and shows TypeError

    TypeError: 'NoneType' object is not callable

    because method_00 points to None and I cannot call None like a function.

  • I use the def keyword to change it from a variable (attribute) to a method

    25class AClass(object):
26
27    attribute_00 = None
28    attribute_01 = None
29    attribute_02 = None
30    attribute_03 = None
31    attribute_04 = None
32    attribute_05 = None
33    attribute_06 = None
34    attribute_07 = None
35    attribute_08 = None
36    attribute_09 = None
37
38    # method_00 = None
39    def method_00():
40        return None

    • the test passes because method_00 is now an attribute/property of the AClass class

    • AClass is an attribute of the attribute_error.py module in the src folder

    • I can call method_00 from outside the file with src.attribute_error.AClass.method_00() or src.attribute_error.AClass().method_00()

REFACTOR: make it better

  • I remove the commented line

    25class AClass(object):
26
27    attribute_00 = None
28    attribute_01 = None
29    attribute_02 = None
30    attribute_03 = None
31    attribute_04 = None
32    attribute_05 = None
33    attribute_06 = None
34    attribute_07 = None
35    attribute_08 = None
36    attribute_09 = None
37
38    def method_00():
39        return None

  • You know the “drill”, I add a line for src.attribute_error.AClass.method_01 to test_attribute_error.py

    43    def test_attribute_error_w_class_methods(self):
44        src.attribute_error.AClass.method_00()
45        src.attribute_error.AClass.method_01
46
47
48# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'method_01'.
                Did you mean: 'method_00'?

  • I add the method to the definition of AClass in attribute_error.py

    25class AClass(object):
26
27    attribute_00 = None
28    attribute_01 = None
29    attribute_02 = None
30    attribute_03 = None
31    attribute_04 = None
32    attribute_05 = None
33    attribute_06 = None
34    attribute_07 = None
35    attribute_08 = None
36    attribute_09 = None
37
38    def method_00():
39        return None
40
41    def method_01():
42        return None

    the test passes because in this case it does not matter if I reference the method (AClass.method_01) or call it (AClass.method_01()).

  • I add a line for src.attribute_error.AClass.method_02 to test_attribute_error.py

    43    def test_attribute_error_w_class_methods(self):
44        src.attribute_error.AClass.method_00()
45        src.attribute_error.AClass.method_01
46        src.attribute_error.AClass().method_02()
47
48
49# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'method_02'.
                Did you mean: 'method_00'?

  • I add the method to the definition of AClass in attribute_error.py

    69    def method_01():
70        return None
71
72    def method_02():
73        return None

    the terminal is my friend, and shows TypeError

    TypeError: AClass.method_02() takes
           0 positional arguments but 1 was given

    because this happens when AClass().method_02() is called

    AClass().method_02()
    AClass.method_02(AClass)

    which raises TypeError since the definition of method_02 does not allow it take any positional arguments (the parentheses are empty).

  • I add self to the parentheses of method_02

    72    # def method_02():
73    def method_02(self):
74        return None

    the test passes because this happens when AClass().method_02() is called

    AClass().method_02()
    AClass.method_02(self)

    where self is AClass.

  • I add the staticmethod decorator method definition instead of self since it does not use anything in the class. That way I do not send more information than what the method needs.

    69    def method_01():
70        return None
71
72    @staticmethod
73    def method_02():
74    # def method_02(self):
75        return None

    the test is still green because this now happens when AClass().method_02() is called

    AClass().method_02()
    AClass.method_02()

    with the staticmethod decorator it does not matter if I call the method from an instance (AClass()) or from the class (AClass).

  • I remove the commented line

    69    def method_01():
70        return None
71
72    @staticmethod
73    def method_02():
74        return None

  • I add a line for src.attribute_error.AClass.method_03 to test_attribute_error.py

    43    def test_attribute_error_w_class_methods(self):
44        src.attribute_error.AClass.method_00()
45        src.attribute_error.AClass.method_01
46        src.attribute_error.AClass().method_02()
47        src.attribute_error.AClass().method_03
48
49
50# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'method_03'.
                Did you mean: 'method_00'?

  • I add the method to the definition of AClass in attribute_error.py

    72    @staticmethod
73    def method_02():
74        return None
75
76    def method_03():
77        return None

    the test passes because in this case I reference the method (AClass().method_03), I do not call it (AClass().method_03()).

  • I add a line for src.attribute_error.AClass.method_04 to test_attribute_error.py

    43    def test_attribute_error_w_class_methods(self):
44        src.attribute_error.AClass.method_00()
45        src.attribute_error.AClass.method_01
46        src.attribute_error.AClass().method_02()
47        src.attribute_error.AClass().method_03
48        src.attribute_error.AClass().method_04()
49
50
51# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'method_04'.
                Did you mean: 'method_00'?

  • I add the method to the definition of AClass in attribute_error.py

    76    def method_03():
77        return None
78
79    def method_04():
80        return None

    the terminal is my friend, and shows TypeError

    TypeError: AClass.method_04() takes
           0 positional arguments but 1 was given

    because this happens when AClass().method_04() is called

    AClass().method_04()
    AClass.method_04(AClass)

    which raises TypeError since the definition of method_04 does not allow it take any positional arguments.

  • I add the staticmethod decorator to the definition for method_04

    76    def method_03():
77        return None
78
79    @staticmethod
80    def method_04():
81        return None

    the test passes because this now happens when AClass().method_04() is called

    AClass().method_04()
    AClass.method_04()

    with the staticmethod decorator it does not matter if I call the method from an instance (AClass()) or from the class (AClass).

  • I add a line for src.attribute_error.AClass.method_05 to test_attribute_error.py

    43    def test_attribute_error_w_class_methods(self):
44        src.attribute_error.AClass.method_00()
45        src.attribute_error.AClass.method_01
46        src.attribute_error.AClass().method_02()
47        src.attribute_error.AClass().method_03
48        src.attribute_error.AClass().method_04()
49        src.attribute_error.AClass.method_05
50
51
52# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'method_05'.
                Did you mean: 'method_00'?

  • I add the method to the definition of AClass in attribute_error.py

    79    @staticmethod
80    def method_04():
81        return None
82
83    def method_05():
84        return None

    the test passes.

  • I add a line for src.attribute_error.AClass.method_06 to test_attribute_error.py

    43    def test_attribute_error_w_class_methods(self):
44        src.attribute_error.AClass.method_00()
45        src.attribute_error.AClass.method_01
46        src.attribute_error.AClass().method_02()
47        src.attribute_error.AClass().method_03
48        src.attribute_error.AClass().method_04()
49        src.attribute_error.AClass.method_05
50        src.attribute_error.AClass.method_06()
51
52
53# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'method_06'.
                Did you mean: 'method_00'?

  • I add the method to the definition of AClass in attribute_error.py

    83    def method_05():
84        return None
85
86    def method_06():
87        return None

    the test passes because this happens when AClass.method_06() is called

    AClass.method_06()

    I called the method with the class (AClass.method_06()) not an instance of the class (AClass().method_06()).

  • I add a line for src.attribute_error.AClass.method_07 to test_attribute_error.py

    43    def test_attribute_error_w_class_methods(self):
44        src.attribute_error.AClass.method_00()
45        src.attribute_error.AClass.method_01
46        src.attribute_error.AClass().method_02()
47        src.attribute_error.AClass().method_03
48        src.attribute_error.AClass().method_04()
49        src.attribute_error.AClass.method_05
50        src.attribute_error.AClass.method_06()
51        src.attribute_error.AClass.method_07
52
53
54# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'method_07'.
                Did you mean: 'method_00'?

  • I add the method to the definition of AClass in attribute_error.py

    86    def method_06():
87        return None
88
89    def method_07():
90        return None

    the test passes.

  • I add a line for src.attribute_error.AClass.method_08 to test_attribute_error.py

    43    def test_attribute_error_w_class_methods(self):
44        src.attribute_error.AClass.method_00()
45        src.attribute_error.AClass.method_01
46        src.attribute_error.AClass().method_02()
47        src.attribute_error.AClass().method_03
48        src.attribute_error.AClass().method_04()
49        src.attribute_error.AClass.method_05
50        src.attribute_error.AClass.method_06()
51        src.attribute_error.AClass.method_07
52        src.attribute_error.AClass().method_08()
53
54
55# Exceptions seen

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'method_08'.
                Did you mean: 'method_00'?

  • I add the method to the definition of AClass in attribute_error.py

    89    def method_07():
90        return None
91
92    def method_08():
93        return None

    the terminal is my friend, and shows TypeError

    TypeError: AClass.method_08() takes
           0 positional arguments but 1 was given

    because this happens when AClass().method_08() is called

    AClass().method_08()
    AClass.method_08(AClass)

    which raises TypeError since the definition of method_08 does not allow it take any positional arguments (the parentheses are empty).

  • I add the staticmethod decorator to the method definition since it does not use anything in the class

    89    def method_07():
90        return None
91
92    @staticmethod
93    def method_08():
94        return None

    the test passes because this now happens when AClass().method_08() is called

    AClass().method_08()
    AClass.method_08()

    with the staticmethod decorator it does not matter if I call the method from an instance (AClass()) or from the class (AClass).

  • I add a line for src.attribute_error.AClass.method_09 to test_attribute_error.py

    43    def test_attribute_error_w_class_methods(self):
44        src.attribute_error.AClass.method_00()
45        src.attribute_error.AClass.method_01
46        src.attribute_error.AClass().method_02()
47        src.attribute_error.AClass().method_03
48        src.attribute_error.AClass().method_04()
49        src.attribute_error.AClass.method_05
50        src.attribute_error.AClass.method_06()
51        src.attribute_error.AClass.method_07
52        src.attribute_error.AClass().method_08()
53        src.attribute_error.AClass().method_09
54
55
56# Exceptions seen
57# AssertionError
58# AttributeError
59# NameError
60# TypeError
61# SyntaxError

    the terminal is my friend, and shows AttributeError

    AttributeError: type object 'AClass'
                has no attribute 'method_09'.
                Did you mean: 'method_00'?

  • I add the method to the definition of AClass in attribute_error.py

    25class AClass(object):
26
27    attribute_00 = None
28    attribute_01 = None
29    attribute_02 = None
30    attribute_03 = None
31    attribute_04 = None
32    attribute_05 = None
33    attribute_06 = None
34    attribute_07 = None
35    attribute_08 = None
36    attribute_09 = None
37
38    def method_00():
39        return None
40
41    def method_01():
42        return None
43
44    @staticmethod
45    def method_02():
46        return None
47
48    def method_03():
49        return None
50
51    @staticmethod
52    def method_04():
53        return None
54
55    def method_05():
56        return None
57
58    def method_06():
59        return None
60
61    def method_07():
62        return None
63
64    @staticmethod
65    def method_08():
66        return None
67
68    def method_09():
69        return None

    the test passes because in this case I reference the method (AClass().method_09), I do not call it (AClass().method_09()).

  • I add a git commit message in the other terminal

    git commit -am \
'add test_attribute_error_w_class_methods'

  • A function in a class is an attribute of the class and is called a method

close the project

  • I close attribute_error.py and test_attribute_error.py

  • I click in the terminal where the tests are running

  • I use q on the keyboard to leave the tests. The terminal goes back to the command line.

  • I change directory to the parent of attribute_error

    cd ..

    the terminal shows

    .../pumping_python

    I am back in the pumping_python directory.

review

All the tests I have run for AttributeError show that because in Python everything is an object

I still have the problem that the tests all show the correct way to use attributes I made in attribute_error.py. If someone reads the file or runs it, there is no way for them to know how the code relates to AttributeError unless they go through the process with me, there has to be a better way.

code from the chapter

Do you want to see all the CODE I typed in this chapter?

what is next?

You know

Would you like to know where the extra attributes and methods of the Person class came from?

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