On Wed, Dec 26, 2012 at 12:16 PM, Nick Coghlan <ncogh...@gmail.com> wrote: > On Wed, Dec 26, 2012 at 6:50 PM, Serhiy Storchaka <storch...@gmail.com> 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 | ncogh...@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 _______________________________________________ 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/archive%40mail-archive.com
