Add python-mixins-course sample code

Publishes the code from the 'Understanding Mixin Classes in Python'
video course so it can be offered as a free email opt-in download to
the YouTube/free audience (course zip is otherwise members-only).

Author: Philipp Acsany

python-mixins-course/README.md

@@ -0,0 +1,3 @@
+# Understanding Mixin Classes in Python
+
+This folder contains sample code for the Real Python video course [Understanding Mixin Classes in Python](https://realpython.com/courses/understanding-mixin-classes-in-python/).

python-mixins-course/as_dict_mixin.py

@@ -0,0 +1,22 @@
+class Person:
+    def __init__(self, name, age):
+        self.name = name
+        self.age = age
+
+    def as_dict(self):
+        return {
+            "name": self.name,
+            "age": self.age,
+        }
+
+
+class Car:
+    def __init__(self, make, model):
+        self.make = make
+        self.model = model
+
+    def as_dict(self):
+        return {
+            "make": self.make,
+            "model": self.model,
+        }

python-mixins-course/as_dict_mixin_final.py

@@ -0,0 +1,23 @@
+class AsDictMixin:
+    def as_dict(self):
+        return vars(self)
+
+
+class Person(AsDictMixin):
+    def __init__(self, name, age):
+        self.name = name
+        self.age = age
+
+
+john = Person("John", 42)
+print(john.as_dict())
+
+
+class Car(AsDictMixin):
+    def __init__(self, make, model):
+        self.make = make
+        self.model = model
+
+
+toyota = Car("Toyota", "Prius")
+print(toyota.as_dict())

python-mixins-course/sequence.py

@@ -0,0 +1,11 @@
+from abc import ABC, abstractmethod
+
+
+class Sequence(ABC):
+    @abstractmethod
+    def __getitem__(self, index):
+        pass
+
+    @abstractmethod
+    def __len__(self):
+        pass

python-mixins-course/sequence_abc.py

@@ -0,0 +1,35 @@
+from abc import ABC, abstractmethod
+
+
+class Sequence(ABC):
+    @abstractmethod
+    def __getitem__(self, index):
+        pass
+
+    @abstractmethod
+    def __len__(self):
+        pass
+
+    def __iter__(self):
+        index = 0
+        while index < len(self):
+            yield self[index]
+            index += 1
+
+
+class MyRange(Sequence):
+    def __init__(self, stop):
+        self.stop = stop  # Assume that `stop` is >= 0.
+
+    def __getitem__(self, index):
+        if 0 <= index < self.stop:
+            return index
+        raise IndexError
+
+    def __len__(self):
+        return self.stop
+
+
+r = MyRange(10)
+for number in r:
+    print(number)

python-mixins-course/sequence_final.py

@@ -0,0 +1,35 @@
+from abc import ABC, abstractmethod
+
+
+class Sequence(ABC):
+    @abstractmethod
+    def __getitem__(self, index):
+        pass
+
+    @abstractmethod
+    def __len__(self):
+        pass
+
+    def __iter__(self):
+        index = 0
+        while index < len(self):
+            yield self[index]
+            index += 1
+
+
+class MyRange(Sequence):
+    def __init__(self, stop):
+        self.stop = stop  # Assume that `stop` is >= 0.
+
+    def __getitem__(self, index):
+        if 0 <= index < self.stop:
+            return index
+        raise IndexError
+
+    def __len__(self):
+        return self.stop
+
+
+r = MyRange(10)
+for number in r:
+    print(number)

python-mixins-course/sequence_mixin.py

@@ -0,0 +1,40 @@
+from abc import ABC, abstractmethod
+
+
+class IterMixin:
+    # __iter__ works IF the class inheriting the mixin
+    # already provides __getitem__ and __len__.
+    def __iter__(self):
+        print("Hey from inside IterMixin.__iter__.")
+        index = 0
+        while index < len(self):
+            yield self[index]
+            index += 1
+
+
+class Sequence(IterMixin, ABC):
+    @abstractmethod
+    def __getitem__(self, index):
+        pass
+
+    @abstractmethod
+    def __len__(self):
+        pass
+
+
+class MyRange(Sequence):
+    def __init__(self, stop):
+        self.stop = stop  # Assume that `stop` is >= 0.
+
+    def __getitem__(self, index):
+        if 0 <= index < self.stop:
+            return index
+        raise IndexError
+
+    def __len__(self):
+        return self.stop
+
+
+r = MyRange(10)
+for number in r:
+    print(number)