a Promise.all methode ?

[gdo]

Hello,

a little question (but I don't know how to setup the question tag :(

Do you have any plan to implemente a Promise.all method ? I make reference to :

all(promises);
Combines multiple promises into a single promise that is resolved when all of the input promises are resolved. 

from $q of angularJS.

Best regards
Ebuprofen

[mighe]

Let me better understand: you're asking for something like

p1 = Promise.execute { ... }
p2 = Promise.execute { ... }
p3 = Promise.execute { ... }

p4 = Promise.after(p1, p2, p3) { |r1, r2, r3| ... }

where r1, r2 and r3 are the results respectively of p1, p2 and p3?

[chrisseaton]

Ha ha that's a data driven future. All these constructs are the same after you look at them long enough (not a bad thing).

[jdantonio]

@gdo Thank you for the suggestion. What you are suggesting is very similar to how Concurrent::dataflow aggregates Futures. If it is something you think would be valuable we'll look into it. We are trying to finalize a 0.6.0 release right now. Perhaps the following release?

[gdo]

thanks for your responses (I love Promise.after)

A dataflow capable of aggregating future and promise would be cool.

[obrok]

I believe this is almost what Promise#zip does (#158). Maybe it would be better to also have Promise.zip or Promise.all and implement one in terms of the other?

[jdantonio]

@obrok Sounds reasonable. Would you like to try to implement it?

[obrok]

@jdantonio Sure

[jdantonio]

I had a great conversation with @dinshaw while at RubyConf. He has been experimenting with promises and had some very nice things to say about our gem. He has a very specific use case for an #all method. He's going to take a look at the current #zip method and see if it will meet his need. If not, we should consider adding an #all method that fits his use case. If we do add it, we should consider @obrok's suggestion and try to implement one in terms of the other (if possible).

I'll take this one on unless someone else would like to volunteer.

[obrok]

Currently there is both #zip and .zip. You just need to Promise.zip(*promises) instead of Promise.all(promises) I think.

[pitr-ch]

Just a note: the new implementation #176 of Future and Promises has both forms:

f1 = future { 1 }; f2 = future { 2 }; f3 = future { 3 }

Future.join(f1, f2, f3)
f1.join f2, f3
f1 + f2

Implementation does not block any thread.