On 23 August 2012 10:05, Mark Carter <alt.mcar...@gmail.com> wrote: > Suppose I want to define a function "safe", which returns the argument > passed if there is no error, and 42 if there is one. So the setup is > something like: > > def safe(x): > # WHAT WOULD DEFINE HERE? > > print safe(666) # prints 666 > print safe(1/0) # prints 42 > > I don't see how such a function could be defined. Is it possible? >
It isn't possible to define a function that will do this as the function will never be called if an exception is raised while evaluating its arguments. Depending on your real problem is a context-manager might do what you want: >>> from contextlib import contextmanager >>> @contextmanager ... def safe(default): ... try: ... yield default ... except: ... pass ... >>> with safe(42) as x: ... x = 1/0 ... >>> x 42 >>> with safe(42) as x: ... x = 'qwe' ... >>> x 'qwe' Oscar
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