最终会在没有 python 的尝试块的情况下阻止工作吗？

Question

If I do not specify any try and except block in python, will finally work in the program?

or I can use finally only with a try block.

if condition:
   print('something')
else:
   print('something else')
finally:
   print('I will always run')

Answer 1

No, it won't work outside a try block, because finally is part of the try statement, as evident from Python's grammar :

try_stmt: ('try' ':' suite
           ((except_clause ':' suite)+
            ['else' ':' suite]
            ['finally' ':' suite] |
           'finally' ':' suite))

So the finally keyword can occur only within the try_stmt production, which captures try statements.

Answer 2

No, finally is only used with try . Its purpose is to run some code after the try and/or any except block, whether or not the code in the try block threw an exception. The finally block is executed immediately after the try or except block, not delayed until the end of the program. See the official docs for a more thorough explanation.

finally is useful if you need to clean up some resources before continuing. For example:

f = open('myfile.txt')
try:
    f.write('blabla')  # This might raise an exception, for example if the disk is full
finally:
    f.close() # Close the file whether the write failed or not.

Without finally we'd have to repeat the cleanup statement, like this:

f = open('myfile.txt')
try:
    f.write('blabla')
except:
    f.close()
    raise
f.close()

In Python, it is almost always better to use a with block instead of try / finally .

Finally, in your example, you might as well write:

if condition:
   print('something')
else:
   print('something else')
print('I will always run')