如何捕獲Try / Catch Block Python中的所有異常？

Question

我正在編寫python代碼來安裝我的程序在linux環境中所需的所有庫包。所以linux可能包含python 2.7或2.6或兩者，所以我開發了一個try和除了塊代碼，將在linux中安裝pip包。 嘗試塊代碼包含python 2.7版本pip install和Catch塊包含python 2.6版本pip install。 我的問題是代碼的和平工作正常，當我試圖在python 2.6中安裝pandas它讓我有些錯誤。 我想抓住那個例外。 你能否告訴我如何改進我的嘗試，除了塊以捕獲該異常

required_libraries = ['pytz','requests','pandas']
try:
   from subprocess import check_output
   pip27_path = subprocess.check_output(['sudo','find','/','-name','pip2.7'])
   lib_installs = [subprocess.call((['sudo',pip27_path.replace('\n',''),'install', i])) for i in required_libraries]
except:
   p = subprocess.Popen(['sudo','find','/','-name','pip2.6'], stdout=subprocess.PIPE);pip26_path, err = p.communicate()
   lib_installs = [subprocess.call((['sudo',pip26_path.replace('\n',''),'install', i])) for i in required_libraries]

Answer 1

您可以使用一個塊捕獲幾個異常。 讓我們對異常使用Exception和ArithmeticError。

try:
    # Do something
    print(q)

# Catch exceptions  
except (Exception, ArithmeticError) as e:
    template = "An exception of type {0} occurred. Arguments:\n{1!r}"
    message = template.format(type(e).__name__, e.args)
    print (message)

如果您需要捕獲幾個異常並自己處理每個異常，那么您將為每個異常編寫一個except語句。

try:
    # Do something
    print(q)

# Catch exceptions  
except Exception as e:
    print (1)

except ArithmeticError as e:
    print (2)

# Code to be executed if the try clause succeeded with no errors or no return/continue/break statement

else:
    print (3)

您還可以檢查異常是否為“MyCustomException”類型，例如使用if語句。

if isinstance(e, MyCustomException):
    # Do something
    print(1)

至於你的問題，我建議將代碼分成兩個函數。

install(required_libraries)

def install(required_libraries, version='pip2.7'):
    # Perform installation
    try:
        from subprocess import check_output
        pip27_path = subprocess.check_output(['sudo','find','/','-name', version])
        lib_installs = [subprocess.call((['sudo',pip27_path.replace('\n',''),'install', i])) for i in required_libraries]

    except Exception as e:
        backup(required_libraries)

def backup(required_libraries, version='pip2.6'):
    try:
        p = subprocess.Popen(['sudo','find','/','-name',version]], stdout=subprocess.PIPE);pip26_path, err = p.communicate()
        lib_installs = [subprocess.call((['sudo',pip26_path.replace('\n',''),'install', i])) for i in required_libraries]

    except Exception as e:
        template = "An exception of type {0} occurred. Arguments:\n{1!r}"
        message = template.format(type(e).__name__, e.args)
        print (message)

        #Handle exception

注意：我沒有測試過這個，我也不是專家，所以我希望我能提供幫助。

有用的鏈接：

1. 內置例外
2. 錯誤和例外
3. 復合語句