On 2009-05-06 19:41:29 -0700, Steven D'Aprano
<ste...@remove.this.cybersource.com.au> said:
On Wed, 06 May 2009 16:40:19 -0700, TomF wrote:
As a relative newcomer to Python, I like it a lot but I'm dismayed at
the difficulty of handling simple errors. In Perl if you want to
anticipate a file-not-found error you can simply do:
open($file) or die("open($file): $!");
and you get an intelligible error message. In Python, to get the same
thing it appears you need at least:
try:
f=open(file)
except IOError, err:
print "open(%s): got %s" % (file, err.strerror)
exit(-1)
Functions never fail silently in Python. (At least built-in functions
never fail silently. Functions you write yourself can do anything you
want.)
Well, yes, I'm aware that if you don't handle errors Python barfs out a
backtrace.
If it fails, you get both a straight-forward error message and a useful
traceback:
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IOError: [Errno 2] No such file or directory: 'foomanchu'
The only reason you would bother going to the time and effort of catching
the error, printing your own error message, and then exiting, is if you
explicitly want to hide the traceback from the user.
Well, to me, exposing the user to such raw backtraces is
unprofessional, which is why I try to catch user-caused errors. But I
suppose I have an answer to my question.
Thanks,
-Tom
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