Having problems with Exceptions

[Thomas Wouters]

On Thu, Jul 06, 2000 at 10:03:44AM -0600, m wrote:

> I'm new at Python coding and am trying to catch
> errors returned by os.open with exception handling.
> All errors with os.open are returned with an OSError
> exception.  So, how do I split out the individual errors
> with something as simple as:

> try:
>   file=os.open("test",os.O_RDWR | os.O_CREAT | os.O_EXCL, 0444)
> 
> except OSError:
>   {want to do different things here for errno EEXIST (file exists)
>      or EACCES (Permission denied), etc.}

> I have looked at the tuple returned by sys.exc_info() and can
> extract the *text* of the Python error message 
> (i.e. "[Errno 17] File exists"), but not the numeric error number.
> I certianly don't want to have to rely on parsing the text to get 
> the actual error.  I'm sure there is an easy answer to this if
> someone would be kind enough to help me.

You're looking for the 'errno' attribute of OSError objects. You should
compare them to constants defined in errno, for compatibility, like so:


import os, errno

try:
    file = os.open("test", ... )
except OSError, e:
    if e.errno == errno.EEXIST:
        print "The file eixsts already"
    elif e.errno == errno.EACCES:
        print "Can't touch this"
    elif e.errno == ELOOP:
        print "symlink after " * 1024 + "symlink!"
    <etc>


-- 
Thomas Wouters <thomas at xs4all.net>

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