On 1/1/2010 3:47 PM, Peng Yu 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?
Simple, when an exception is thrown and I don't catch it, the exception
terminates the program immediately and I got a traceback showing the
point of failure. When I return error value and I don't check for it, I
passed passed errors silently and gets a traceback forty-two lines later
when trying to use the resources I failed to acquire forty-two lines prior.
> Is it because the efficiency
> is not the primary goal of python?
Efficiency is not primary goal of python, but since python encourages
EAFP (Easier to Ask Forgiveness than Permission); the design decisions
chosen makes setting up a try-block much cheaper than a language
designed over LBYL (Look Before You Leap) and return codes.
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