> I'm missing how this would help ...
With callbacks it may be something like code below:
> so you'll still need to attach the two error handlers, and you'll still
need
> to handle the possibility of multiple notifications.
Not sure about it but maybe `stream.destroy()` on first event should handle
such cases.
var copy = function(from, to, cb){
var fromStream = null
var toStream = null
var finish = function(err){
fromStream.destroy()
toStream.destroy()
cb(err)
}
fromStream = fs.createReadStream(from, function(err){
if(err) return cb(err)
toStream = fs.createWriteStream(to, function(err){
if(err) return cb(err)
fromStream.on('error', finish)
toStream.on('error', finish)
fromStream.on('end', finish)
fromStream.pipe(toStream)
})
})
}
On Monday, October 8, 2012 6:41:43 AM UTC+4, Martin Cooper wrote:
>
> On Sun, Oct 7, 2012 at 5:54 PM, Alexey Petrushin
> <[email protected] <javascript:>> wrote:
> > Tried to copy files using streams and pipe and got funny results. Let's
> > consider following code (highlighted version
> https://gist.github.com/3850106
> > ):
> >
> > var copy = function(from, to, cb){
> > var fromStream = fs.createReadStream(from)
> > fromStream.on('error', cb)
> > var toStream = fs.createWriteStream(to)
> > toStream.on('error', cb)
> > fromStream.on('end', cb)
> > }
> >
> > copy('non existing file a', 'non existing dir/file b',
> function(err){
> > console.log(err)
> > })
> >
> > There are errors in both streams (non existing source file and no parent
> > directory for destination file) - so, both of them will emit
> > 'error' event, and the callback will be called twice with both errors.
> >
> > // Error will be reported twice:
> > //
> > // { [Error: ENOENT, open 'non existing file a'] errno: 34,
> > // code: 'ENOENT', path: 'non existing file a' }
> > // { [Error: ENOENT, open 'non existing dir/file b'] errno: 34,
> > // code: 'ENOENT', path: 'non existing dir/file b' }
> >
> > I found the solution by looking at the source of `util.pump` - it does
> it by
> > wrapping callback into function that calls callback only once - for the
> fist
> > error and ignoring others.
> >
> > But maybe it would be nice to have a callback for `createXxxStream` or
> > something like 'ready' or 'success' events to know that it created
> > successfully?
>
> I'm missing how this would help. If there was such an event, either
> stream could still emit an error before it (e.g. open error) or after
> it (e.g. read or write error), so you'll still need to attach the two
> error handlers, and you'll still need to handle the possibility of
> multiple notifications. What would be the benefit of having another
> event to listen for?
>
> --
> Martin Cooper
>
>
> > --
> > Job Board: http://jobs.nodejs.org/
> > Posting guidelines:
> > https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines
> > You received this message because you are subscribed to the Google
> > Groups "nodejs" group.
> > To post to this group, send email to [email protected]<javascript:>
> > To unsubscribe from this group, send email to
> > [email protected] <javascript:>
> > For more options, visit this group at
> > http://groups.google.com/group/nodejs?hl=en?hl=en
>
--
Job Board: http://jobs.nodejs.org/
Posting guidelines:
https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines
You received this message because you are subscribed to the Google
Groups "nodejs" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/nodejs?hl=en?hl=en
