I'm so glad to see more interest in using generators in node.js. I've experimented with this style of programming a *lot*. I even went so far as to re-implement node.js in the lua language (luvit.io) and attempted to implement it on top of SpiderMonkey (luvmonkey) because both VMs already have co-routines/generators.
I know this question has already been answered, but I wanted to share my solution as I ran into the same issue using generators for some js-git related examples. https://github.com/creationix/git-repo/blob/master/example/create.js The relevant part of that file is where I loop over nested objects and create git history from them. This involves I/O (and thus yielding) at all levels of the nested loops. run(function* main() { // Configure the repo API to work from a local clone. var repo = yield gitRepo({ fs: fs("./test-repo.git"), bare: true, init: true }); console.log("Git database Initialized"); var parent; yield* each(commits, function* (message, files) { // Start building a tree object. var tree = {}; yield* each(files, function* (name, contents) { // Save the file in the database and store the hash in the tree data. tree[name] = { mode: 0100644, hash: yield repo.save({ blob: { length: contents.length, source: create(contents) } }) }; }); var commit = { tree: yield repo.save({tree: tree}), parent: parent, author: author + " " + gitDate(new Date), committer: committer + " " + gitDate(new Date), message: message }; if (!parent) delete commit.parent; parent = yield repo.save({commit: commit}); yield repo.updateHead(parent); }); }); // Generator friendly forEach for objects function* each(object, callback) { var keys = Object.keys(object); for (var i = 0, l = keys.length; i < l; i++) { var key = keys[i]; yield* callback(key, object[key]); } } As you can see, I had to create a simple "each" helper that worked like forEach, but worked in terms of yielding generators. P.S. I know you were hoping for the community to standardize on one helper soon, but I feel it's far to premature for that. Generators don't work in any stable release of node and even the unstable releases require a flag to use it. There is more to explore in this area, especially generator based streams once they land in a stable release and not behind a flag. P.P.S I too wrote a simple generator helper based on the gist I wrote that galaxy is inspired from. Mine is called "gen-run" https://github.com/creationix/gen-run. Another one that seems popular is TJ's "co" https://github.com/visionmedia/co -Tim Caswell On Mon, Jul 15, 2013 at 2:11 AM, cpprototypes <cpprototy...@gmail.com>wrote: > Thanks for the replies, I have a better understanding now of how these > libraries are using generators. I hope that one of these types of > libraries becomes as popular as the async library and "standard" within the > node community. This way of writing async code is much more elegant than > the current way of using only callbacks and can help expand node.js usage > into other areas. For instance, the script example I wrote is part of a > larger command line script I was writing to test some services. Such > scripting tends to follow a synchronous flow. I got really frustrated > while writing it in an async way (since the natural flow is synchronous, it > maps very poorly to the current callback-only style, even libraries like > async don't help much). I eventually gave up and quickly wrote the script > in python because I had to get the task done for the day. But I want > node.js to eventually take python's place in my tool set. So I went back > and tried it again with this new generators feature and it was going well > until I ran into this issue. Some may say that such use is beyond the > scope of node.js, but I think JS and node.js have potential to be more than > just network async programming. > > > > On Friday, July 12, 2013 2:47:28 PM UTC-7, cpprototypes wrote: >> >> I'm using node 0.11.3 with --harmony-generators to try the new feature. >> I found two libraries that should help use existing node callback-based >> code with generators (suspend and galaxy). The code I'm trying to run was >> similar to the following: >> >> (using suspend) >> >> var fs = require('fs'); >> var request = require('request'); >> >> suspend(function* (resume) { >> var contents = yield fs.readFile('idList.json', 'utf8', resume); >> contents.split('\n').forEach(**function(id) { >> var info = yield >> request.get('http://www.**example.com?id='+id<http://www.example.com?id='+id>, >> resume); >> }); >> })(); >> >> (using galaxy) >> >> var galaxy = require('galaxy'); >> var fs = galaxy.star(require('fs')); >> var request = galaxy.star(require('request')**); >> >> function* main() { >> var contents = yield fs.readFile('idList.json', 'utf8'); >> contents.split('\n').forEach(**function(id) { >> var info = yield >> request.get('http://www.**example.com?id='+id<http://www.example.com?id='+id> >> ); >> }); >> }; >> >> galaxy.unstar(main)(function(**err, result) { >> console.log('done'); >> }); >> >> Using either library, when node tries to execute the get request ("var >> info = yield request.get...") it exits with the following error: >> >> SyntaxError: Unexpected identifier >> >> And the error highlights the "request" part in "var info = yield >> request.get..." I'm guessing that the creation of the new function scope >> in the forEach is somehow causing an issue. But I'm not sure why it's not >> working. >> >> >> -- > -- > Job Board: http://jobs.nodejs.org/ > Posting guidelines: > https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines > You received this message because you are subscribed to the Google > Groups "nodejs" group. > To post to this group, send email to nodejs@googlegroups.com > To unsubscribe from this group, send email to > nodejs+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/nodejs?hl=en?hl=en > > --- > You received this message because you are subscribed to the Google Groups > "nodejs" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to nodejs+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/groups/opt_out. > > > -- -- Job Board: http://jobs.nodejs.org/ Posting guidelines: https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines You received this message because you are subscribed to the Google Groups "nodejs" group. 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