：value = first([f1, f2, f3, ..., fn], default='All Failed')
#!/usr/bin/env
def first(flist, default=None):
""" Try each function in `flist` until one does not throw an exception, and
return the return value of that function. If all functions throw exceptions,
return `default`
Args:
flist - list of functions to try
default - value to return if all functions fail
Returns:
return value of first function that does not throw exception, or
`default` if all throw exceptions.
TODO: Also accept a list of (f, (exceptions)) tuples, where f is the
function as above and (exceptions) is a tuple of exceptions that f should
expect. This allows you to still re-raise unexpected exceptions.
"""
for f in flist:
try:
return f()
except:
continue
else:
return default
# Testing.
def f():
raise TypeError
def g():
raise IndexError
def h():
return 1
# We skip two exception-throwing functions and return value of the last.
assert first([f, g, h]) == 1
assert first([f, g, f], default='monty') == 'monty'
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