Update decorators materials for resurfacing

primer-on-python-decorators/README.md

@@ -1,17 +1,11 @@
 # Primer on Python Decorators
 
-Code examples from the [Primer on Python Decorators](https://realpython.com/primer-on-python-decorators/) tutorial on [Real Python](https://realpython.com/).
+Here you can find code examples from the [Primer on Python Decorators](https://realpython.com/primer-on-python-decorators/) tutorial on [Real Python](https://realpython.com/).
 
 ## Decorators
 
-As noted in the article, most decorators are stored in the file [`decorators.py`](https://github.com/realpython/materials/blob/master/primer-on-python-decorators/decorators.py). The exceptions are those decorators that depend on third party packages ([Flask](http://flask.pocoo.org/) and [Pint](https://pint.readthedocs.io/)), which are available in [`decorators_flask.py`](https://github.com/realpython/materials/blob/master/primer-on-python-decorators/decorators_flask.py) and [`decorators_unit.py`](https://github.com/realpython/materials/blob/master/primer-on-python-decorators/decorators_unit.py), respectively.
+You can find most decorators in the file `decorators.py`. The exceptions are those decorators that depend on the third-party packages ([Flask](http://flask.pocoo.org/) and [Pint](https://pint.readthedocs.io/)). These decorators are available in `secret_app.py`, `validate_input.py`, and `units.py`.
 
 ## Examples
 
-Most of the code examples from the article are available in the [`examples.py`](https://github.com/realpython/materials/blob/master/primer-on-python-decorators/examples.py) file.
-
-## Cheat Sheet
-
-We’ve put together a short & sweet Python decorators cheat sheet for you that summarizes the techniques explained in this tutorial:
-
-[Get the decorators cheat sheet »](https://realpython.com/optins/view/decorators-cheatsheet/)
+You can find many code examples from the tutorial in separate Python files.

primer-on-python-decorators/calculate_e.py

@@ -0,0 +1,13 @@
+import math
+
+from decorators import debug
+
+math.factorial = debug(math.factorial)
+
+
+def approximate_e(terms=18):
+    return sum(1 / math.factorial(n) for n in range(terms))
+
+
+if __name__ == "__main__":
+    print(approximate_e(5))

primer-on-python-decorators/circle.py

@@ -0,0 +1,35 @@
+class Circle:
+    def __init__(self, radius):
+        self.radius = radius
+
+    @property
+    def radius(self):
+        """Get value of radius"""
+        return self._radius
+
+    @radius.setter
+    def radius(self, value):
+        """Set radius, raise error if negative"""
+        if value >= 0:
+            self._radius = value
+        else:
+            raise ValueError("radius must be non-negative")
+
+    @property
+    def area(self):
+        """Calculate area inside circle"""
+        return self.pi() * self.radius**2
+
+    def cylinder_volume(self, height):
+        """Calculate volume of cylinder with circle as base"""
+        return self.area * height
+
+    @classmethod
+    def unit_circle(cls):
+        """Factory method creating a circle with radius 1"""
+        return cls(1)
+
+    @staticmethod
+    def pi():
+        """Value of π, could use math.pi instead though"""
+        return 3.1415926535

primer-on-python-decorators/class_decorators.py

@@ -0,0 +1,22 @@
+from decorators import debug, timer
+
+
+class TimeWaster:
+    @debug
+    def __init__(self, max_num):
+        self.max_num = max_num
+
+    @timer
+    def waste_time(self, num_times):
+        for _ in range(num_times):
+            sum([number**2 for number in range(self.max_num)])
+
+
+@timer
+class TimeWaster2:
+    def __init__(self, max_num):
+        self.max_num = max_num
+
+    def waste_time(self, num_times):
+        for _ in range(num_times):
+            sum([i**2 for i in range(self.max_num)])

primer-on-python-decorators/decorators.py

@@ -1,21 +1,10 @@
-"""Examples of decorators
-
-See https://realpython.com/primer-on-python-decorators/
-
-The decorators with dependencies outside of the standard library (Flask
-and Pint) are available in separate files.
-"""
-
 import functools
 import time
 
-
-PLUGINS = dict()  # Dictionary used by @register to store plugins
+PLUGINS = dict()
 
 
 def do_twice(func):
-    """Run the decorated function twice"""
-
     @functools.wraps(func)
     def wrapper_do_twice(*args, **kwargs):
         func(*args, **kwargs)
@@ -33,7 +22,7 @@ def wrapper_timer(*args, **kwargs):
         value = func(*args, **kwargs)
         end_time = time.perf_counter()
         run_time = end_time - start_time
-        print(f"Finished {func.__name__!r} in {run_time:.4f} secs")
+        print(f"Finished {func.__name__}() in {run_time:.4f} secs")
         return value
 
     return wrapper_timer
@@ -45,25 +34,25 @@ def debug(func):
     @functools.wraps(func)
     def wrapper_debug(*args, **kwargs):
         args_repr = [repr(a) for a in args]
-        kwargs_repr = [f"{k}={v!r}" for k, v in kwargs.items()]
+        kwargs_repr = [f"{k}={repr(v)}" for k, v in kwargs.items()]
         signature = ", ".join(args_repr + kwargs_repr)
         print(f"Calling {func.__name__}({signature})")
         value = func(*args, **kwargs)
-        print(f"{func.__name__!r} returned {value!r}")
+        print(f"{func.__name__}() returned {repr(value)}")
         return value
 
     return wrapper_debug
 
 
-def slow_down_1sec(func):
+def slow_down_one_second(func):
     """Sleep 1 second before calling the function"""
 
     @functools.wraps(func)
-    def wrapper_slow_down(*args, **kwargs):
+    def wrapper_slow_down_one_second(*args, **kwargs):
         time.sleep(1)
         return func(*args, **kwargs)
 
-    return wrapper_slow_down
+    return wrapper_slow_down_one_second
 
 
 def register(func):
@@ -73,8 +62,6 @@ def register(func):
 
 
 def repeat(_func=None, *, num_times=2):
-    """Run the decorated function the given number of times"""
-
     def decorator_repeat(func):
         @functools.wraps(func)
         def wrapper_repeat(*args, **kwargs):
@@ -91,29 +78,25 @@ def wrapper_repeat(*args, **kwargs):
 
 
 def count_calls(func):
-    """Count the number of calls made to the decorated function"""
-
     @functools.wraps(func)
     def wrapper_count_calls(*args, **kwargs):
         wrapper_count_calls.num_calls += 1
-        print(f"Call {wrapper_count_calls.num_calls} of {func.__name__!r}")
+        print(f"Call {wrapper_count_calls.num_calls} of {func.__name__}()")
         return func(*args, **kwargs)
 
     wrapper_count_calls.num_calls = 0
     return wrapper_count_calls
 
 
 class CountCalls:
-    """Count the number of calls made to the decorated function"""
-
     def __init__(self, func):
         functools.update_wrapper(self, func)
         self.func = func
         self.num_calls = 0
 
     def __call__(self, *args, **kwargs):
         self.num_calls += 1
-        print(f"Call {self.num_calls} of {self.func.__name__!r}")
+        print(f"Call {self.num_calls} of {self.func.__name__}()")
         return self.func(*args, **kwargs)
 
 
@@ -139,7 +122,7 @@ def singleton(cls):
 
     @functools.wraps(cls)
     def wrapper_singleton(*args, **kwargs):
-        if not wrapper_singleton.instance:
+        if wrapper_singleton.instance is None:
             wrapper_singleton.instance = cls(*args, **kwargs)
         return wrapper_singleton.instance
 
@@ -157,15 +140,5 @@ def wrapper_cache(*args, **kwargs):
             wrapper_cache.cache[cache_key] = func(*args, **kwargs)
         return wrapper_cache.cache[cache_key]
 
-    wrapper_cache.cache = dict()
+    wrapper_cache.cache = {}
     return wrapper_cache
-
-
-def set_unit(unit):
-    """Register a unit on a function"""
-
-    def decorator_set_unit(func):
-        func.unit = unit
-        return func
-
-    return decorator_set_unit