On Wed, Dec 26, 2012 at 12:16 PM, Nick Coghlan
On Wed, Dec 26, 2012 at 6:50 PM, Serhiy Storchaka
wrote: On 25.12.12 23:55, Andrew Svetlov wrote:
Currently we have exception tree of classes inherited from OSError When we use C API we can call PyErr_SetFromErrno and PyErr_SetFromErrnoWithFilename[Object] functions. This ones raise concrete exception class (FileNotFoundError for example) looking on implicit errno value. I cannot see the way to do it from python.
raise OSError(errno.ENOENT, 'No such file or directory', 'qwerty') Traceback (most recent call last): File "<stdin>", line 1, in <module> FileNotFoundError: [Errno 2] No such file or directory: 'qwerty'
As Serhiy's example shows, this mapping of error numbers to subclasses is implemented directly in OSError.__new__. We did this so that code could catch the new exceptions, even when dealing with old code that raises the legacy exception types.
Sorry. Looks like OSError.__new__ requires at least two arguments for executing subclass search mechanism:
OSError(errno.ENOENT) OSError(2,) OSError(errno.ENOENT, 'error msg') FileNotFoundError(2, 'error msg')
I had tried first one and got confuse.
http://docs.python.org/3/library/exceptions#OSError could probably do with an example like the one quoted in order to make this clearer
Added http://bugs.python.org/issue16785 for this.
Cheers, Nick.
-- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/andrew.svetlov%40gmail.com
-- Thanks, Andrew Svetlov