Python Koan 131引發異常

我正在通過Python Koans學習Python，並且提出了在Python中引發異常的問題。具體來說，我經歷了koan後甚至與try...except...混淆。我知道對Rudy Koan Ruby Koan 151 raising exceptions有類似的問題。但我是一個Python新手，對Ruby一無所知。Python Koan 131引發異常

因此，這裏的公案：

# You need to finish implementing triangle() in the file 'triangle.py' 
from triangle import * 

class AboutTriangleProject2(Koan): 
    # The first assignment did not talk about how to handle errors. 
    # Let's handle that part now. 
    def test_illegal_triangles_throw_exceptions(self): 
     # Calls triangle(0, 0, 0) 
     self.assertRaises(TriangleError, triangle, 0, 0, 0) 

     self.assertRaises(TriangleError, triangle, 3, 4, -5) 
     self.assertRaises(TriangleError, triangle, 1, 1, 3) 
     self.assertRaises(TriangleError, triangle, 2, 4, 2)

以下是triangle.py

def triangle(a, b, c): 
    # DELETE 'PASS' AND WRITE THIS CODE 

    if a == b and b == c and c == a: 
     return 'equilateral' 
    if a == b or b == c or a == c: 
     return 'isosceles' 
    else: 
     return 'scalene' 

# Error class used in part 2. No need to change this code. 
class TriangleError(StandardError): 
    pass

我應該完成triangle()功能。

據我的理解，try...except...的功能就像是如果滿足某些標準然後做某件事，否則通過例外。那麼在我的情況下，我應該使用if ... then raise TriangleError還是try... except ...？他們之間有什麼不同？

非常感謝！

來源

2011-09-13 Sean

您想要使用raise，這會導致創建一個異常，並沿着調用堆棧向前移動，直到通過try/except塊處理異常爲止。例如，如果你在真正的代碼中使用此三角函數，你會做這樣的事情

try: 
    t = triangle(x, y, z) 
    ... 
except TriangleError: 
    print 'Triangle', x, y, z, 'is no good!'

這樣，你能處理錯誤時壞的三角形被做和你的程序將不會崩潰。

來源

2011-09-13 08:16:43

請看下面的答案：

def triangle(a, b, c): 
    # DELETE 'PASS' AND WRITE THIS CODE 
    if min([a,b,c])<=0: 
     raise TriangleError 
    x,y,z = sorted([a,b,c]) 
    if x+y<=z: 
     raise TriangleError 
    if a==b and b==c and c==a: 
     return 'equilateral' 
    if a==b or b==c or a==c: 
     return 'isosceles' 
    else: 
     return 'scalene'

來源

2012-12-04 10:59:14 oon

這裏是我的代碼，它的工作

def triangle(a, b, c): 
# DELETE 'PASS' AND WRITE THIS CODE 
if min([a,b,c])<=0: 
    raise TriangleError,"no <0 numbers" 

if sorted([a,b,c])[0]+sorted([a,b,c])[1]<=sorted([a,b,c])[2]: 
    raise TriangleError,"sf" 

set_a=set(([a,b,c])) 
if len(set_a)==1: 
    return 'equilateral' 
elif len(set_a)==2: 
    return 'isosceles' 
elif len(set_a)==3: 
    return 'scalene' 

# Error class used in part 2. No need to change this code. 
class TriangleError(StandardError): 
    pass

來源

2014-02-20 08:21:49

我結束了類似南希的答案的東西，使用集，而不是比較A，B和手動，並且它也可以工作。

def triangle(a, b, c): 
    # DELETE 'PASS' AND WRITE THIS CODE 
    ls = sorted([a,b,c]) 
    if min(ls)<=0 or ls[0]+ls[1]<=ls[2]: raise TriangleError, 'Triángulo mal formado.' 
    l = len(list(set(ls))) 
    if(l==1): return 'equilateral' 
    if(l==2): return 'isosceles' 
    if(l==3): return 'scalene' 

# Error class used in part 2. No need to change this code. 
class TriangleError(StandardError): 
    pass

來源

2014-09-04 15:07:15

Python Koan 131引發異常

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