How to properly ignore exceptions
try: doSomething()except: pass
try: doSomething()except Exception: pass
The difference is that the first one will also catch
SystemExit and stuff like that, which are derived directly from
See documentation for details:
It's generally considered best-practice to only catch the errors you are interested in. In the case of
shutil.rmtree it's probably
"/fake/dir")Traceback (most recent call last): [...]OSError: [Errno 2] No such file or directory: '/fake/dir'shutil.rmtree(
If you want to silently ignore that error, you would do:
try: shutil.rmtree(path)except OSError: pass
Why? Say you (somehow) accidently pass the function an integer instead of a string, like:
It will give the error "TypeError: coercing to Unicode: need string or buffer, int found" - you probably don't want to ignore that, which can be difficult to debug.
If you definitely want to ignore all errors, catch
Exception rather than a bare
except: statement. Again, why?
Not specifying an exception catches every exception, including the
SystemExit exception which for example
try: sys.exit(1)except: pass>>>
Compare this to the following, which correctly exits:
try: sys.exit(1)except Exception: passshell:~$
If you want to write ever better behaving code, the
OSError exception can represent various errors, but in the example above we only want to ignore
Errno 2, so we could be even more specific:
import errnotry: shutil.rmtree(path)except OSError as e: if e.errno != errno.ENOENT: # ignore "No such file or directory", but re-raise other errors raise
When you just want to do a try catch without handling the exception, how do you do it in Python?
It depends on what you mean by "handling."
If you mean to catch it without taking any action, the code you posted will work.
If you mean that you want to take action on an exception without stopping the exception from going up the stack, then you want something like this:
try: do_something()except: handle_exception() raise #re-raise the exact same exception that was thrown