On 2020-04-07 10:12 p.m., Soni L. wrote:
the fact that exception handlers aren't reusable and composable is
really bothering me so I would like to propose something to make them
reusable and composable.
for example, if I have this mess:
def get_property_values(self, prop):
try:
factory = self.get_supported_properties()[prop]
except KeyError as exc:
raise PropertyError from exc
iterator = factory(self._obj)
try:
first = next(iterator)
except StopIteration:
return (x for x in ())
except abdl.exceptions.ValidationError as exc:
raise LookupError from exc
return itertools.chain([first], iterator)
I get to refactor it into:
def keyerror_handler(exc):
raise PropertyError from exc
def other_handler(exc):
if isinstance(exc, StopIteration):
return (x for x in ())
raise LookupError from exc
def get_property_values(self, prop):
try:
factory = self.get_supported_properties()[prop]
except KeyError with keyerror_handler:
pass
iterator = factory(self._obj)
try:
first = next(iterator)
except (StopIteration, abdl.exceptions.ValidationError) with
other_handler as result:
return result
return itertools.chain([first], iterator)
and the handlers become reusable!
another idea would be to use semicolons:
def get_property_values(self, prop):
try:
factory = self.get_supported_properties()[prop]
except KeyError with keyerror_handler;
iterator = factory(self._obj)
try:
first = next(iterator)
except abdl.exceptions.ValidationError with validation_handler;
except StopIteration:
return (x for x in ())
return itertools.chain([first], iterator)
but nobody likes semicolons
I sent too soon. here's also something that would be nice:
def get_property_values(self, prop):
try:
factory = self.get_supported_properties()[prop]
except KeyError with keyerror_handler;
iterator = factory(self._obj)
try:
first = next(iterator)
except abdl.exceptions.ValidationError with validation_handler;
except StopIteration with stop_handler as return
return itertools.chain([first], iterator)
(using "return" as the result target for the handler. doesn't need
semicolon, as it can't be ambiguous.)
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