contextmanager - Trying to understand python with statement and context managers

Question

I am new to this, and am just trying to understand the with statement. I understand that it is supposed to replace the try/except block.

Now suppose I do something like this:

try:
   name='rubicon'/2 # to raise an exception
except Exception as e:
   print "no not possible"
finally:
   print "Ok I caught you"

How do I replace this with a context manager?

Answer 1

with doesn't really replace try/except, but, rather, try/finally. Still, you can make a context manager do something different in exception cases from non-exception ones:

class Mgr(object):
    def __enter__(self): pass
    def __exit__(self, ext, exv, trb):
        if ext is not None: print "no not possible"
        print "OK I caught you"
        return True

with Mgr():
    name='rubicon'/2 #to raise an exception

The return True part is where the context manager decides to suppress the exception (as you do by not re-raising it in your except clause).