TR1 Initial commit

python-isinstance/README.md

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+# How Does `isinstance()` Work in Python?
+
+This folder provides the code examples for the Real Python tutorial [How Does `isinstance()` Work in Python?](https://realpython.com/how-does-python-isinstance-work/).
+
+The `.py` files contain the code found in the tutorial. 
+
+When setting up your tutorial environment, make sure `balls.py`, `balls_v2.py` and `customiterables.py` are in your program folder.  You'll need to import content from these during the tutorial.
+
+

python-isinstance/abstract_class_failure.py

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+from balls_v2 import Ball
+
+test_ball = Ball("white", "sphere")

python-isinstance/ball_instance_test.py

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+from balls import Ball, FootBall, PoolBall
+
+eight_ball = PoolBall("black", 8)
+football = FootBall("brown")
+ball = Ball("green", "sphere")
+
+isinstance(eight_ball, PoolBall)
+isinstance(eight_ball, Ball)
+isinstance(eight_ball, FootBall)
+
+isinstance(eight_ball, object)
+isinstance(football, object)
+isinstance(ball, object)
+isinstance(object, object)

python-isinstance/balls.py

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+from abc import ABC, abstractmethod
+
+
+class Ball(ABC):
+    def __init__(self, color, shape):
+        self.color = color
+        self.shape = shape
+
+    @abstractmethod
+    def get_shape(self):
+        pass
+
+
+class PoolBall(Ball):
+    def __init__(self, color, number):
+        super().__init__(color, shape="sphere")
+        self.number = number
+
+    def get_shape(self):
+        return self.shape
+
+
+class AmericanFootBall(Ball):
+    def __init__(self, color):
+        super().__init__(color, shape="elongated ellipsoid")
+
+    def get_shape(self):
+        return "Elongated Ellipsoid"

python-isinstance/balls_v2.py

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+from abc import ABC, abstractmethod
+
+
+class Ball(ABC):
+    def __init__(self, color, shape):
+        self.color = color
+        self.shape = shape
+
+    @abstractmethod
+    def get_shape(self):
+        pass
+
+
+class PoolBall(Ball):
+    def __init__(self, color, number):
+        super().__init__(color, shape="sphere")
+        self.number = number
+
+    def get_shape(self):
+        return self.shape
+
+
+class AmericanFootBall(Ball):
+    def __init__(self, color):
+        super().__init__(color, shape="elongated ellipsoid")
+
+    def get_shape(self):
+        return "Elongated Ellipsoid"

python-isinstance/basic_iterable.py

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+squares = [
+    1,
+    4,
+    9,
+]
+
+for _ in squares:
+    print(_)

python-isinstance/bool_int_test.py

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+isinstance(True, int)
+
+isinstance(True, bool)
+
+isinstance(False, int)
+
+isinstance(False, bool)
+
+test_data = [10, True, False]
+
+for element in test_data:
+    "int" if isinstance(element, int) else "bool"
+
+for element in test_data:
+    "bool" if isinstance(element, bool) else "int"
+
+# Try and avoid this.
+# for element in test_data:
+#     "bool" if type(element) is bool else "int"

python-isinstance/consolidation1_solution.py

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+from balls import Ball, FootBall, PoolBall
+
+football = FootBall("brown")
+ball = Ball("green", "sphere")
+
+
+isinstance(football, FootBall)
+
+isinstance(football, PoolBall)
+
+isinstance(ball, Ball)
+
+isinstance(ball, FootBall)
+
+isinstance(football, Ball)
+
+isinstance(ball, PoolBall)
+
+isinstance(1, bool)
+
+isinstance(0, bool)

python-isinstance/consolidation2_solution.py

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+from abc import ABC
+from collections.abc import Callable
+
+from balls_v2 import AmericanFootBall, PoolBall
+
+eight_ball = PoolBall("black", 8)
+football = AmericanFootBall("brown")
+
+isinstance(eight_ball, ABC)
+
+isinstance(football, ABC)
+
+isinstance(isinstance, Callable)
+
+isinstance(eight_ball.get_shape, Callable)
+
+isinstance(PoolBall, Callable)

python-isinstance/customiterable_one_tests.py

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+from collections.abc import Iterable
+
+from customiterables import CustomIterableOne
+
+for number in CustomIterableOne(4):
+    print(number)
+
+
+isinstance(CustomIterableOne(4), Iterable)

python-isinstance/customiterable_three_tests.py

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+from collections.abc import Iterable
+
+from customiterables import CustomIterableThree
+
+for number in CustomIterableThree(4):
+    print(number)
+
+
+isinstance(CustomIterableThree(4), Iterable)

python-isinstance/customiterable_two_tests.py

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+from collections.abc import Iterable
+
+from customiterables import CustomIterableTwo
+
+for number in CustomIterableTwo(4):
+    print(number)
+
+isinstance(CustomIterableTwo(4), Iterable)

python-isinstance/customiterables.py

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+from collections.abc import Iterable
+
+
+class CustomIterableOne(Iterable):
+
+    def __init__(self, last_value):
+        self.last_value = last_value
+        self.current = 1
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        if self.current <= self.last_value:
+            value = self.current
+            self.current += 1
+            return value
+        else:
+            raise StopIteration()
+
+
+class CustomIterableTwo:
+
+    def __init__(self, last_value):
+        self.last_value = last_value
+        self.current = 1
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        if self.current <= self.last_value:
+            value = self.current
+            self.current += 1
+            return value
+        else:
+            raise StopIteration()
+
+
+class CustomIterableThree:
+
+    def __init__(self, last_value):
+        self.last_value = last_value
+
+    def __getitem__(self, index):
+        if index >= self.last_value:
+            raise IndexError
+        return index + 1

python-isinstance/invalid_types.py

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+def calculate_area(length, breadth):
+    return length * breadth
+
+
+calculate_area(5, 3)
+calculate_area(5, "3")
+calculate_area("5", "3")

python-isinstance/isinstance_abc.py

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+from balls_v2 import AmericanFootBall, Ball, PoolBall
+
+eight_ball = PoolBall("black", 8)
+
+football = AmericanFootBall("brown")
+
+isinstance(eight_ball, Ball)
+
+isinstance(football, Ball)

python-isinstance/iter_test.py

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+from customiterables import (CustomIterableOne, CustomIterableThree,
+                             CustomIterableTwo)
+
+iter(CustomIterableOne(4))
+
+iter(CustomIterableTwo(4))
+
+iter(CustomIterableThree(4))
+
+iter(100)
+

python-isinstance/multiple_type_tests.py

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+"Number" if isinstance(3.14, (int, float)) else "Not a number"
+
+"Number" if isinstance("3.14", (int, float)) else "Not a number"
+
+"Number" if isinstance(3.14, ((int, float), (bool,))) else "Not a number"
+
+"Number" if isinstance(3.14, (int, float, bool)) else "Not a number"
+
+"Number" if isinstance(3.14, int | float) else "Not a number"
+
+"Number" if isinstance("3.14", int | float) else "Not a number"

python-isinstance/type_testing.py

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+shape = "sphere"
+number = 8
+
+isinstance(shape, str)
+
+isinstance(number, int)
+
+isinstance(number, float)

python-isinstance/type_tests.py

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+from balls import Ball, PoolBall
+
+eight_ball = PoolBall("black", 8)
+
+type(eight_ball)
+
+type(eight_ball) is PoolBall
+
+
+isinstance(eight_ball, Ball)
+
+type(eight_ball) is Ball

python-isinstance/validating_types.py

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+def calculate_area(length, breadth):
+    if isinstance(length, int) and isinstance(breadth, int):
+        return length * breadth
+    return "Invalid argument"
+
+
+calculate_area(5, 3)
+
+calculate_area(5, "3")
+
+calculate_area("5", "3")