Feature Request: chan.select()

[eugeneware]

Feature Request: chan.select()

[brentropy]

I am glad you like chan. I can see how the select functionality could be useful. I will look in to adding something like this. Thanks for the suggestion Eugene.

[eugeneware]

Hi Brent, I actually had another idea about how to achieve the same result, as it's more a synchronization issue of multiple yieldables in co, so I wrote a simple module called co-select that can do the job:

var co = require('co'),
    select = require('co-select'),
    chan = require('chan');
co(function *(){
  var ch1 = chan(),
      ch2 = chan();

  var first = yield select([ch1, ch2]);
  switch (first.caller) {
    case ch1:
      var val1 = first.value;
      break;

    case ch2:
      var val2 = first.value;
      break;
  }
})();

If you just want the first value from a channel, you can pass true through as the last argument:

var co = require('co'),
    select = require('co-select'),
    chan = require('chan');
co(function *(){
  var ch1 = chan(),
      ch2 = chan();

  var firstValue = yield select([ch1, ch2], true);
})();

[eugeneware]

Oops. Spoke too soon. co-select won't actually solve the issue, because if a value from ch1 is read, then we lose the future value from ch2.

So, probably needs to be implemented in the chan library where you have knowledge of the channel state and don't have to actually read from all the channels in advance to determine which one is ready to be read.

[eugeneware]

I had a crack at adding select() to chan in #8

[brentropy]

Resolved by pull request #9. Merged.