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From: "Prasad, Ramit" <ramit.prasad@jpmchase.com>
To: "'Andrew Berg'" <bahamutzero8825@gmail.com>, "'python-list@python.org'" <python-list@python.org>
Date: Wed, 11 May 2011 14:50:00 -0400
Subject: RE: Proper way to handle errors in a module
Thread-Topic: Proper way to handle errors in a module
Thread-Index: AcwQCv+BwGTlb6sARmS5amk8zLXoFgAALeVg
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The simple but code heavy system is to create two functions=2E One that rai=
ses an error and one that returns None or something that is mutually agreed=
 to be invalid=2E  You can even get away with one of them doing the actual =
work and the other one just as a wrapper=2E I feel too lazy to fix the mist=
akes below, but you get the idea=2E=0D=0A=0D=0A Def a():=0D=0A	Blahblah=0D=
=0A	Raise SomeError=0D=0A=0D=0ADef b():=0D=0A	Try:=0D=0A		A()=0D=0A	Except =
SomeError:=0D=0A		Return blah=0D=0A=0D=0A=0D=0ARamit=0D=0A=0D=0A=0D=0A=0D=
=0ARamit Prasad | JPMorgan Chase Investment Bank | Currencies Technology=0D=
=0A712 Main Street | Houston, TX 77002=0D=0Awork phone: 713 - 216 - 5423=0D=
=0A=0D=0A=0D=0A-----Original Message-----=0D=0AFrom: python-list-bounces+ra=
mit=2Eprasad=3Djpmchase=2Ecom@python=2Eorg [mailto:python-list-bounces+rami=
t=2Eprasad=3Djpmchase=2Ecom@python=2Eorg] On Behalf Of Andrew Berg=0D=0ASen=
t: Wednesday, May 11, 2011 1:15 PM=0D=0ATo: python-list@python=2Eorg=0D=0AS=
ubject: Re: Proper way to handle errors in a module=0D=0A=0D=0AOn 2011=2E05=
=2E11 12:57 PM, Patty wrote:=0D=0A> Hi Andrew -=0D=0A>=0D=0A> Sometimes you=
 want an exception come up and then use that information to =0D=0A> take yo=
ur=0D=0A> program in some direction=2E=0D=0ARight, but I'm wondering how I =
should handle errors in a module, where=0D=0Adifferent people will want the=
ir programs to do different things when an=0D=0Aerror occurs in a function =
or method from my module (which is not=0D=0Anecessarily because of a bug in=
 my module - the calling script could=0D=0Asend a bad parameter or some sys=
tem configuration could prevent the=0D=0Afunction from doing something)=2E =
On one hand, I could let almost all=0D=0Aexceptions go unhandled and have t=
he calling script handle them=2E This=0D=0Awould force the developer of the=
 calling script to learn all the=0D=0Aexceptions that my module could raise=
 (which could be really annoying if=0D=0AI have custom exceptions for probl=
ems that don't otherwise raise an=0D=0Aexception)=2E OTOH, I could handle a=
ll the exceptions and return None or=0D=0Asome default value, but that woul=
d make it harder for the developer to=0D=0Amake the script react appropriat=
ely=2E=0D=0A-- =0D=0Ahttp://mail=2Epython=2Eorg/mailman/listinfo/python-lis=
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