Merge pull request #654 from realpython/python-dict-attribute

Sample code for the article on `.__dict__`

Author: brendaweles

python-dict-attribute/README.md

@@ -0,0 +1,3 @@
+# Using Python's `.__dict__` to Work With Attributes
+
+This folder provides the code examples for the Real Python tutorial [Using Python's `.__dict__` to Work With Attributes](https://realpython.com/python-dict-attribute/).

python-dict-attribute/class_inheritance.py

@@ -0,0 +1,16 @@
+class Parent:
+    def __init__(self):
+        self.parent_attr = "parent"
+
+
+class Child(Parent):
+    def __init__(self):
+        super().__init__()
+        self.child_attr = "child"
+
+
+parent = Parent()
+print(parent.__dict__)
+
+child = Child()
+print(child.__dict__)

python-dict-attribute/config_v1.py

@@ -0,0 +1,16 @@
+class Config:
+    def __init__(self, **kwargs):
+        self.__dict__.update(kwargs)
+
+    update = __init__
+
+    def __str__(self):
+        return str(self.__dict__)
+
+
+config = Config(theme="light", font_size=12, language="English")
+print(config)
+
+user = {"theme": "dark", "font_size": 14, "language": "Spanish"}
+config.update(**user)
+print(config)

python-dict-attribute/config_v2.py

@@ -0,0 +1,33 @@
+class Config:
+    def __init__(self, name):
+        self.name = name
+
+    def set_option(self, key, value):
+        self.__dict__[key] = value
+
+    def get_option(self, key):
+        return self.__dict__.get(key, None)
+
+    def remove_option(self, key):
+        if key in self.__dict__:
+            del self.__dict__[key]
+            # self.__dict__.pop(key)
+            print(f"'{key}' removed!")
+        else:
+            print(f"'{key}' does not exist.")
+
+    def clear(self):
+        self.__dict__.clear()
+        print("All options removed!")
+
+
+conf = Config("GUI App")
+conf.set_option("theme", "dark")
+conf.set_option("size", "200x400")
+print(conf.__dict__)
+conf.remove_option("size")
+print(conf.__dict__)
+conf.remove_option("autosave")
+print(conf.__dict__)
+conf.clear()
+print(conf.__dict__)

python-dict-attribute/config_v3.py

@@ -0,0 +1,33 @@
+class Config:
+    def __init__(self, name):
+        self.name = name
+
+    def set_option(self, key, value):
+        setattr(self, key, value)
+
+    def get_option(self, key):
+        return getattr(self, key, None)
+
+    def remove_option(self, key):
+        if hasattr(self, key):
+            delattr(self, key)
+            print(f"'{key}' removed!")
+        else:
+            print(f"'{key}' does not exist.")
+
+    def clear(self):
+        for key in list(self.__dict__.keys()):
+            delattr(self, key)
+        print("All options removed!")
+
+
+conf = Config("GUI App")
+conf.set_option("theme", "dark")
+conf.set_option("size", "200x400")
+print(conf.__dict__)
+conf.remove_option("size")
+print(conf.__dict__)
+conf.remove_option("autosave")  # Raises KeyError
+print(conf.__dict__)
+conf.clear()
+print(conf.__dict__)

python-dict-attribute/demo.py

@@ -0,0 +1,13 @@
+class DemoClass:
+    class_attr = "This is a class attribute"
+
+    def __init__(self):
+        self.instance_attr = "This is an instance attribute"
+
+    def method(self):
+        return "This is a method"
+
+
+print(DemoClass.__dict__)
+demo_object = DemoClass()
+print(demo_object.__dict__)

python-dict-attribute/fibonacci.py

@@ -0,0 +1,27 @@
+import time
+
+
+def fibonacci_of_v1(n):
+    if n <= 1:
+        return n
+    return fibonacci_of_v1(n - 1) + fibonacci_of_v1(n - 2)
+
+
+start = time.perf_counter()
+fibonacci_of_v1(35)
+end = time.perf_counter()
+print(f"{end - start:.3f} seconds")
+
+
+def fibonacci_of_v2(n):
+    cache = fibonacci_of_v2.__dict__.setdefault("cache", {})
+    if n in cache:
+        return cache[n]
+    cache[n] = n if n <= 1 else fibonacci_of_v2(n - 1) + fibonacci_of_v2(n - 2)
+    return cache[n]
+
+
+start = time.perf_counter()
+fibonacci_of_v2(35)
+end = time.perf_counter()
+print(f"{end - start:.3f} seconds")

python-dict-attribute/person.py

@@ -0,0 +1,29 @@
+class Person:
+    def __init__(self, first_name, last_name, age):
+        self.first_name = first_name
+        self.last_name = last_name
+        self.age = age
+
+    def __str__(self):
+        return "{first_name} {last_name} is {age} years old".format(
+            **self.__dict__
+        )
+
+    def __repr__(self):
+        return "{cls}('{first_name}', '{last_name}', {age})".format(
+            cls=type(self).__name__,
+            **self.__dict__,
+        )
+
+    def as_dict(self):
+        return self.__dict__
+
+    def as_tuple(self):
+        return tuple(self.__dict__.values())
+
+
+john = Person("John", "Doe", 30)
+print(repr(john))
+print(john)
+print(john.as_dict())
+print(john.as_tuple())

python-dict-attribute/record.py

@@ -0,0 +1,48 @@
+import logging
+
+logging.basicConfig(level=logging.INFO, format="%(message)s")
+
+
+class Record:
+    def __init__(self, **fields):
+        logging.info(f"[INIT] Creating record with fields: {fields}")
+        self.__dict__.update(fields)
+
+    def __getattribute__(self, key):
+        if key == "__dict__":
+            return super().__getattribute__(key)
+        value = super().__getattribute__(key)
+        logging.info(f"[GET] Accessing '{key}' → {value}")
+        return value
+
+    def __setattr__(self, key, value):
+        if key in self.__dict__:
+            logging.info(f"[UPDATE] Modifying '{key}' → {value}")
+        else:
+            logging.info(f"[SET] Creating '{key}' → {value}")
+        self.__dict__[key] = value
+
+    def __delattr__(self, key):
+        if key in self.__dict__:
+            logging.info(f"[DEL] Deleting '{key}'")
+            del self.__dict__[key]
+        else:
+            logging.warning(
+                f"[DEL] Attempted to delete non-existent field '{key}'"
+            )
+
+
+jane = Record(first_name="Jane", last_name="Doe", age=25)
+
+# Access
+print(jane.first_name)
+print(jane.age)
+
+# Mutations
+jane.age = 26
+jane.job = "Software Engineer"
+print(jane.__dict__)
+
+# Deletion
+del jane.age
+print(jane.__dict__)

python-dict-attribute/salary.py

@@ -0,0 +1,14 @@
+class Employee:
+    def __init__(self, name, department, salary):
+        self.name = name
+        self.department = department
+        self.salary = salary
+
+    def give_raise(self, amount):
+        self.salery = self.salary + amount  # Typo here: self.salery
+
+
+john = Employee("John", "Engineering", 70000)
+john.give_raise(5000)
+print(john.salary)
+print(john.__dict__)