On 07/09/2014 08:35 AM, Ben Hoyt wrote:
One issue with option #2 that I just realized -- does scandir yield the
entry at all if there's a stat error? It
can't really, because the caller will expect the .lstat attribute to be
set (assuming he asked for type='lstat') but
it won't be. Is effectively removing these entries just because the stat
failed a problem? I kind of think it is. If
so, is there a way to solve it with option #2?
Leave it up to the onerror handler. If it returns None, skip yielding the
entry, otherwise yield whatever it returned
-- which also means the error handler should be able to set fields on the
DirEntry:
def log_err(exc, entry):
logger.warn("Cannot stat {}".format(exc.filename))
entry.lstat.st_size = 0
return True
This is an interesting idea, but it's just getting more and more
complex, and I'm guessing that being able to change the attributes of
DirEntry will make the C implementation more complex.
Also, I'm not sure it's very workable. For log_err above, you'd
actually have to do something like this, right?
def log_err(exc, entry):
logger.warn("Cannot stat {}".format(exc.filename))
entry.lstat = os.stat_result((0, 0, 0, 0, 0, 0, 0, 0, 0, 0))
return entry
I would imagine we would provide a helper function:
def stat_result(st_size=0, st_atime=0, st_mtime=0, ...):
return os.stat_result((st_size, st_atime, st_mtime, ...))
and then in onerror
entry.lstat = stat_result()
Unless there's another simple way around this issue, I'm back to
loving the simplicity of option #1, which avoids this whole question.
Too simple is just as bad as too complex, and properly handling errors is rarely a simple task. Either we provide a
clean way to deal with errors in the API, or we force every user everywhere to come up with their own system.
Also, just because we provide it doesn't force people to use it, but if we
don't provide it then people cannot use it.
To summarize the choice I think we are looking at:
1) We provide a very basic tool that many will have to write wrappers
around to get the desired behavior (choice 1)
2) We provide a more advanced tool that, in many cases, can be used
as-is, and is also fairly easy to extend to handle odd situations
(choice 2)
More specifically, if we go with choice 1 (no built-in error handling, no mutable DirEntry), how would I implement
choice 2? Would I have to write my own CustomDirEntry object?
--
~Ethan~
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