How to handle errors without err callback argument

[joliss]

The following code:

var concat = require('concat-stream')
var through = require('through')

var stream = through().pause()
stream.pipe(concat(function(data) {}))
stream.emit('error')

throws

stream.js:94
      throw er; // Unhandled stream error in pipe.
            ^
undefined

Before d530532, I believe there would have been an err argument to the callback.

It seems a bit surprising to me to have no err argument to the callback. Is there a nice way to handle errors now? Or should we bring the err argument back maybe?

[max-mapper]

Cc @substack (I will respond in more detail later)

Sent from my iPhone

On May 25, 2013, at 12:18 AM, Jo Liss notifications@github.com wrote:

The following code:

var concat = require('concat-stream')
var through = require('through')

var stream = through().pause()
stream.pipe(concat(function(data) {}))
stream.emit('error')
throws

stream.js:94
throw er; // Unhandled stream error in pipe.
^
undefined
Before d530532, I believe there would have been an err argument to the callback.

It seems a bit surprising to me to have no err argument to the callback. Is there a nice way to handle errors now? Or should we bring the err argument back maybe?

—
Reply to this email directly or view it on GitHub.

[jkroso]

i'd also like to hear the story behind it

[max-mapper]

sorry about the lag on responding!

so originally I had an err in the callback but @substack convinced me that it was out of scope for this module. For example, add this line to @joliss' example:

stream.on('error', handleError)

all concat-stream does is combine data events, and it itself isn't a stream, so the error event shouldn't propagate. Instead the error handling can just happen in the upstream stream.

gonna close this for now but feel free to re-open if this description isn't logical

[jkroso]

I can't say I'm convinced, though handling errors separately isn't hard work I'd be inclined to stick with the older version because its more normal to me

[joliss]

Hm, I'd be worried that people just forget to attach error handlers. Anyways, I'll defer to your judgment.