add decorator example

Author: tswast

2021/06-python-decorator/decorator_sample.py

@@ -0,0 +1,43 @@
+# Copyright 2021 Google LLC
+# 
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+# 
+#     https://www.apache.org/licenses/LICENSE-2.0
+# 
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import time
+import functools
+
+
+def memoize(func):
+    answers = {}
+    
+    @functools.wraps(func)
+    def memoized(n):
+        if n not in answers:
+            answers[n] = func(n)
+        return answers[n]
+
+    return memoized
+
+
+@memoize
+def fibonacci(n):
+    if n <= 2:
+        return 1
+    return fibonacci(n - 1) + fibonacci(n - 2)
+
+start = time.perf_counter()
+fib = fibonacci(40)
+end = time.perf_counter()
+
+print(fib)
+print(end - start)
+