Hello!
I have been thinking about how write exception safe constructors in
Python. By exception safe I mean a constructor that does not leak
resources when an exception is raised within it. The following is an
example of one possible way to do it:
class Foo(object):
def __init__(self, name, fail=False):
self.name = name
if not fail:
print '%s.__init__(%s)' % (self.__class__.__name__,
self.name)
else:
print '%s.__init__(%s), FAIL' % (self.__class__.__name__,
self.name)
raise Exception()
def close(self):
print '%s.close(%s)' % (self.__class__.__name__, self.name)
class Bar(object):
def __init__(self):
try:
self.a = Foo('a')
self.b = Foo('b', fail=True)
except:
self.close()
def close(self):
if hasattr(self, 'a'):
self.a.close()
if hasattr(self, 'b'):
self.b.close()
bar = Bar()
As you can see this is less than straight forward. Is there some kind
of best practice that I'm not aware of?
:.:: mattias
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