I found a somewhat simple pattern that seems to work for me:

function processSequential(r, processFn) {
  function getNext() {
    var res = r.read();
    if (res)
      processFn(res, getNext);
    else
      r.once('readable', getNext);
  }
  getNext();
}

And calling it:

processSequential(r, function(buf, cb) {
  // do stuff
  cb();
});

I'm thinking about putting this into an npm module.

On 02/07/2013, at 11.38, Gil Pedersen <gp...@gpost.dk> wrote:

> Thanks, this looks like a somewhat interesting pattern. Looking at it, things 
> quickly get complicated:
> 
> I need to loop, so I'll wrap it in a method, calling it recursively.
> I don't want to call doAsync when bytes === null.
> I can't "kick" when bytes === null, since I get an infinite recursive loop.
> Depending on internal stream state, kicking will not always trigger a 
> 'readable' emit, leading to a stall.
> 
> I really wish this was simpler :-/
> 
> On 02/07/2013, at 09.28, Floby <florent.j...@gmail.com> wrote:
> 
>> I'd use some kind of withReadable(stream, fn) helper
>> 
>> var bytes = stream.read(2);
>> doAsync(bytes, function(err, res) {
>>   withReadable(stream, function () {
>>     // stream is readable for sure
>>   });
>> });
>> 
>> function withReadable(stream, callback) {
>>   stream.once(callback);
>>   stream.read(0);
>> }
>> 
>> 
>> On Monday, 1 July 2013 15:23:44 UTC+2, Gil Pedersen wrote:
>> Hi, 
>> 
>> I have a case where I want to consume a Readable, by: 
>> 
>> 1. Read n bytes. 
>> 2. Process buffer using a function with an async callback. 
>> 3. When callback completes, goto 1. 
>> 
>> I fail to see any simple solution to what I feel must be a somewhat common 
>> use case. The standard "on('readable', function() { this.read(); ... })" 
>> doesn't apply, as I have no way of deferring future 'readable' emits once I 
>> have returned from the handler. 
>> 
>> Can it really be that the most sensible solution is to fall back to the old 
>> API, using pause() and resume()? or have I missed something? 
>> 
>> Regards, 
>> Gil
> 

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