Python Try/except/finally__python

A little summary, otherwise always forget.

x = ' abc '
def fetcher (obj, index): Return
    Obj[index]

fetcher (x, 4)

Output:

  File "test.py", line 6, in <module>
    fetcher (x, 4)
  file "test.py", line 4, in Fetcher return
    obj[index]
  indexerror:string index out of range

the first: Try not only catches exceptions, but also resumes execution

Def catcher ():
    try:
        fetcher (x, 4)
    except:
        print "got Exception"
    print "continuing"

Output:

Got exception
continuing

Second: No matter whether a try or not an exception, finally always execute

Def catcher ():
    try:
        fetcher (x, 4)
    finally:
        print ' after Fecth '

Output:

After Fecth
Traceback (most recent called last):
  file "test.py", line <module>
    catcher ()
  file "test.py", line, in catcher
    Fetcher (x, 4)
  File "test.py", line 4, in Fetcher return
    Obj[index]
IndexEr Ror:string index out of range

Third: Try no exception to execute else

Def catcher ():
    try:
        fetcher (x, 4)
    except:
        print "got Exception"
    else:
        print "not exception

Output:

Got exception

Def catcher ():
    try:
        fetcher (x, 2)
    except:
        print "got Exception"
    else:
        print "not exception

Output:

Not exception

Else action: There is no else statement, and when the try statement is executed, it is not known whether an exception has occurred, or an exception has occurred and has been processed. Separated by what else can be clear.

Fourth: Using raise to pass exceptions

Def catcher ():
    try:
        fetcher (x, 4)
    except:
        print "got Exception"
        raise

Output:

Got exception
Traceback (most recent call last):
  File "test.py", line Notoginseng, in <module>
    catcher ()
  File "test.py", line, in catcher
    Fetcher (x, 4)
  File "test.py", line 4, in Fetcher return
    Obj[index]
Indexerror:string index out of range

When the raise statement does not include an exception name or additional data, the current exception is raised again. If you want to catch a handle to an exception, and you don't want to

The exception disappears in the program code and can be raise again by using the.

Fifth: Except (name1, name2)

Def catcher ():
    try:
        fetcher (x, 4)
    except (TypeError, indexerror):
        print "got Exception"
    else:
        print "not exception"

Captures the exceptions listed in the list for processing. If there are no arguments after except, all exceptions are caught.

Def catcher ():
    try:
        fetcher (x, 4)
    except:
        print "got Exception"