#Potok
Potok is a promise-based replacement for object stream. Potok instance accepts values (or promises which resolution) will be processed by user-defined handlers.
- Documentation (so far, auto-generated from unit tests)
- cujojs/when - Promise implementation Potok is using
###Potoki are using promises
var potok_a = Potok({each: function(promise){ return promise.then(process); } });
potok_a.enter(Promise.resolve('foo'));
potok_a.enter('foo');
potok_a.enter(Promise.reject(new Error('bar')));
assert(when.isPromiseLike(potok_a.ended()));###Potoki are indempotent When chaining, it does not matter how many promises potok you are chaining to already
The following:
potok_a.chain(potok_b);
potok_a.enter('foo');
potok_a.end();potok_a.enter('foo');
potok_a.end();
potok_a.chain(potok_b);potok_a.chain(potok_b);
setTimeout(function(){
potok_a.enter('foo');
potok_a.end();
}, Math.random()*10000);potok_a.enter('foo');
potok_a.end();
setTimeout(function(){potok_a.chain(potok_b);}, Math.random()*10000);all have the same effect: same promises will be passed through both potok_a and potok_b.
###Potoki are chainable
var potok_a = new Potok({ eachFulfilled:function(e){return e+' was here!';} });
var potok_b = new Potok({ eachFulfilled:funcion(e){console.log(e); return e;} });
potok_a.enter('foo');
potok_a.enter('bar');
potok_a.chain(potok_b);
potok_a.end();will log:
foo was here!
bar was here!
###Potoki have built-in error handling
Any rejected task will go through from the point it was entered into the chain to the end, passing through all each and eachRejected handlers.
var potok_a = new Potok({}); //no-op potok, just because, pass through
var potok_b = new Potok({
// do something only with fullfiled tasks
eachFulfilled: function(value){
console.log('%s has passed here!', value); return value;
}
});
var potok_c = new Potok({
// do something only with rejected tasks
eachRejected: function(error){
console.log('Oh noes! %s', error.message);
// null by default is removed from potok
return null;
}
});
potok_a.chain(potok_b).chain(potok_c);
potok_a.enter('foo');
potok_a.enter(when.reject(new Error('All your errs is behandled')));
potok_a.enter('bar');
// .end ends the potok, and .ended returns a promise that will resolve
// when potok_a's handlers work is done
potok_a.end().ended().done()###Potoki can be filtered
var potok = new Potok({});
//returns promise for array with only rejected results
potok.onlyRejected();
//returns promise for array with only fulfilled results
potok.onlyFulfilled();
//returns promise for either all fulfilled results, or with a rejection reason if any task rejected
potok.failOnReject(); ###Potoki can be combined
var potok_a = Potok({});
var potok_b = Potok({});
var potok_c = Potok({});
potok_a.enter('foo');
potok_b.enter('bar');
potok_c.enter('baz');
potok_a.end();
potok_b.end();
potok_c.end();
var combined = Potok.combine([potok_a, potok_b, potok_c]);
when.all(combined.ended()).then(console.log);Outputs [ 'foo', 'bar', 'baz' ].