excepter

jackzhenguo · jackzhenguo · commit 22cffc50ca11 · 2019-12-21T10:33:18.000+08:00
diff --git a/md/统计异常发生次数和时间的装饰器.md b/md/统计异常发生次数和时间的装饰器.md
@@ -0,0 +1,81 @@
+
+写一个装饰器，统计某个异常重复出现指定次数时，经历的时长。
+```python
+import time
+import math
+
+
+def excepter(f):
+    i = 0
+    t1 = time.time()
+    def wrapper(): 
+        try:
+            f()
+        except Exception as e:
+            nonlocal i
+            i += 1
+            print(f'{e.args[0]}: {i}')
+            t2 = time.time()
+            if i == n:
+                print(f'spending time:{round(t2-t1,2)}')
+    return wrapper
+
+```
+
+关键词`nonlocal`常用于函数嵌套中，声明变量i为非局部变量；
+
+如果不声明，`i+=1`表明`i`为函数`wrapper`内的局部变量，因为在`i+=1`引用(reference)时,`i`未被声明，所以会报`unreferenced variable`的错误。
+
+使用创建的装饰函数`excepter`, `n`是异常出现的次数。
+
+共测试了两类常见的异常：`被零除`和`数组越界`。
+
+```python
+n = 10 # except count
+
+@excepter
+def divide_zero_except():
+    time.sleep(0.1)
+    j = 1/(40-20*2)
+
+# test zero divived except
+for _ in range(n):
+    divide_zero_except()
+
+
+@excepter
+def outof_range_except():
+    a = [1,3,5]
+    time.sleep(0.1)
+    print(a[3])
+# test out of range except
+for _ in range(n):
+    outof_range_except()
+
+```
+
+打印出来的结果如下：
+```python
+division by zero: 1
+division by zero: 2
+division by zero: 3
+division by zero: 4
+division by zero: 5
+division by zero: 6
+division by zero: 7
+division by zero: 8
+division by zero: 9
+division by zero: 10
+spending time:1.01
+list index out of range: 1
+list index out of range: 2
+list index out of range: 3
+list index out of range: 4
+list index out of range: 5
+list index out of range: 6
+list index out of range: 7
+list index out of range: 8
+list index out of range: 9
+list index out of range: 10
+spending time:1.01
+```
diff --git a/src/excepter.py b/src/excepter.py
@@ -0,0 +1,45 @@
+import time
+import math
+
+
+def excepter(f):
+    i = 0
+    t1 = time.time()
+
+    def wrapper():
+        try:
+            f()
+        except Exception as e:
+            nonlocal i
+            i += 1
+            print(f'{e.args[0]}: {i}')
+            t2 = time.time()
+            if i == n:
+                print(f'spending time:{round(t2-t1,2)}')
+    return wrapper
+
+
+n = 10  # except count
+
+
+@excepter
+def divide_zero_except():
+    time.sleep(0.1)
+    j = 1/(40-20*2)
+
+
+# test zero divived except
+for _ in range(n):
+    divide_zero_except()
+
+
+@excepter
+def outof_range_except():
+    a = [1, 3, 5]
+    time.sleep(0.1)
+    print(a[3])
+
+
+# test out of range except
+for _ in range(n):
+    outof_range_except()
