Exception as the primary error handling mechanism?

[Diez B. Roggisch]

Peng Yu schrieb:
> On Thu, Dec 31, 2009 at 11:24 PM, Chris Rebert <clp2 at rebertia.com> wrote:
>> On Thu, Dec 31, 2009 at 8:47 PM, Peng Yu <pengyu.ut at gmail.com> wrote:
>>> I observe that python library primarily use exception for error
>>> handling rather than use error code.
>>>
>>> In the article API Design Matters by Michi Henning
>>>
>>> Communications of the ACM
>>> Vol. 52 No. 5, Pages 46-56
>>> 10.1145/1506409.1506424
>>> http://cacm.acm.org/magazines/2009/5/24646-api-design-matters/fulltext
>>>
>>> It says "Another popular design flaw—namely, throwing exceptions for
>>> expected outcomes—also causes inefficiencies because catching and
>>> handling exceptions is almost always slower than testing a return
>>> value."
>>>
>>> My observation is contradicted to the above statement by Henning. If
>>> my observation is wrong, please just ignore my question below.
>>>
>>> Otherwise, could some python expert explain to me why exception is
>>> widely used for error handling in python? Is it because the efficiency
>>> is not the primary goal of python?
>> Correct; programmer efficiency is a more important goal for Python instead.
>> Python is ~60-100x slower than C;[1] if someone is worried by the
>> inefficiency caused by exceptions, then they're using completely the
>> wrong language.
> 
> Could somebody let me know how the python calls and exceptions are
> dispatched? Is there a reference for it?

The source?

http://python.org/ftp/python/2.6.4/Python-2.6.4.tgz

These are really deep internals that - if they really concern you - need 
intensive studies, not casual reading of introductionary documents. IMHO 
you shouldn't worry, but then, there's a lot things you seem to care I 
wouldn't... :)

Diez