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From: "Prasad, Ramit" <ramit.prasad@jpmorgan.com>
To: "python-list@python.org" <python-list@python.org>
Subject: RE: Context Manager getting str instead of AttributeError instance
Thread-Topic: Context Manager getting str instead of AttributeError instance
Thread-Index: Ac0C0ee2HWpMrUyoSZqdW3mY/u0AugADC2TOAAA7KnA=
Date: Thu, 15 Mar 2012 19:10:59 +0000
References: <5B80DD153D7D744689F57F4FB69AF474026B9264@SCACMX008.exchad.jpmchase.net> <jjte9l$4iq$1@dough.gmane.org>
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> Prasad, Ramit wrote:=0D=0A> =0D=0A> > So I have a context manager used to=
 catch errors=0D=0A> >=0D=0A> > def __exit__( self, exceptionClass, excepti=
on, tracebackObject ):=0D=0A> >     if isinstance( exception, self=2Eexcept=
ionClasses ):=0D=0A> >          #do something here=0D=0A> >=0D=0A> > Normal=
ly exception would be the exception instance, but for=0D=0A> > AttributeErr=
or it seems to be a string instead=2E=0D=0A> =0D=0A> I don't think so:=0D=
=0A> =0D=0A> >>> class A(object):=0D=0A> =2E=2E=2E     def __enter__(self):=
 return self=0D=0A> =2E=2E=2E     def __exit__(self, *args): print args=0D=
=0A> =2E=2E=2E=0D=0A> >>> with A() as a:=0D=0A> =2E=2E=2E     a=2Ex=0D=0A> =
=2E=2E=2E=0D=0A> (<type 'exceptions=2EAttributeError'>, AttributeError("'A'=
 object has no=0D=0A> attribute 'x'",), <traceback object at 0x7f57b70f22d8=
>)=0D=0A> Traceback (most recent call last):=0D=0A>   File "<stdin>", line =
2, in <module>=0D=0A> AttributeError: 'A' object has no attribute 'x'=0D=0A=
> =0D=0A> > 1) Why is AttributeError different than the other built-ins=0D=
=0A> > in this respect?=0D=0A> > 2) Are there other standard errors like th=
is (I know=0D=0A> > that SystemExit is different as well)?=0D=0A> > 3) Taki=
ng into account that I want to include subclasses of=0D=0A> > classes liste=
d in self=2EexceptionClasses, Is there a better check I can=0D=0A> > use?=
=0D=0A=0D=0ANot sure why mine behaves differently:=0D=0APython 2=2E6=2E6 (r=
266:84292, Dec 17 2010, 12:36:53) [MSC v=2E1500 32 bit (Intel)] on win32=0D=
=0A>>> =0D=0A>>> class A(object):=0D=0A=2E=2E=2E     def __enter__(self): r=
eturn self=0D=0A=2E=2E=2E     def __exit__(self, *args): print args=0D=0A=
=2E=2E=2E     =0D=0A>>> with A() as a:=0D=0A=2E=2E=2E     a=2Ex=0D=0A=2E=2E=
=2E     =0D=0A(<type 'exceptions=2EAttributeError'>, "'A' object has no att=
ribute 'x'", <traceback object at 0x1817F648>)=0D=0AAttributeError: 'A' obj=
ect has no attribute 'x'=0D=0A=0D=0AAs you can see, I am getting a string w=
hile you are not=2E =0D=0A=0D=0ARamit=0D=0A=0D=0A=0D=0ARamit Prasad | JPMor=
gan Chase Investment Bank | Currencies Technology=0D=0A712 Main Street | Ho=
uston, TX 77002=0D=0Awork phone: 713 - 216 - 5423=0D=0A=0D=0A--=0D=0A=0D=0A=
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