I think you meant "closure". clojure is a language running on JVM.
On Wednesday, December 12, 2012 6:59:56 PM UTC+8, greelgorke wrote: > > why? its the simpliest and most common way, that's it. passing by custom > params has to be implemented in the async function itself, there is no > native support in js nor node for this. and since use of clojures is very > common in js world, mostly noone cares about it. but yes it may help to > un-clutter the callbacks a bit and helpt to build pure functions with > explicit parameters. but i doubt that it would be a performance > improvement, because v8 optimized clojurescope-access very well, see here > http://jsperf.com/bind-vs-clojure/2 > > Am Mittwoch, 12. Dezember 2012 10:36:29 UTC+1 schrieb Michael Hasenstein: >> >> This is not a technical question (I'm quite clear about how the stuff >> works). I also did some (Google) research before asking. >> >> I'm just curious if there is a good reason that I just fail to see... I >> AM aware that very obviously I am not the first person to think about this, >> but I just could not find ANY good explanation for the "WHY". >> >> Let me just give an example. >> >> I get an array of strings (filenames, e.g. from fs.readDir), and now I >> want to process them: fs.stat(), fs.readFile(), then minify, then >> fs.writeFile(). >> >> now. all those operations are asynchronous unless I use the sync-version >> of those functions. >> >> PROBLEM: >> >> I really, really, REALLY need that filename string it all started with in >> the other functions - so now, with node.js callback API being as it is, I >> have to write code that I really, REALLY dislike, because it seems >> suboptimal compared to what I COULD do. >> >> What I COULD do but which the node.js callbacks don't allow is the >> passing of additional parameters to my callback. >> >> Code: >> function onStat(err, stat) { >> if (stat.isFile()) { >> //fs.readFile(...)... WHICH FILE???? >> } >> } >> >> files.forEach(function (file) { >> fs.stat(<some path> + file), onStat); >> }); >> >> I AM AWARE HOW TO SOLVE THIS. Pls. don't reply showing me how I can >> easily solve this with additional function scopes. >> >> My issue with adding additional functions is that that solution SUCKS. If >> I could just add additional parameters to the fs.stat() call which my >> callback gets as 3rd, 4th, etc parameter (or an array or an object, >> whatever) the sun would still shine. >> >> However, node.js makes me add additional quite useless scopes. >> ALTERNATIVELY I write all those callback functions into the lexical scope >> of the forEach() - that's what has been called "callback hell" for a long >> time - no way. >> >> So, can anyone enlighten me - and I MAY INDEED be simply incredibly >> stupid not to see the point without help - why node.js could not just let >> me add custom parameters for callbacks? Again: additional scope-producing >> functions are NOT OPTIMAL IMHO - it produces overhead both in the code and >> during runtime. There MUST be a reason, otherwise by now, node.js almost at >> version 0.9, would have been changed, wouldn't it? I mean, libraries like >> YUI3 give me the option to add my own custom parameters to be passed down >> to callback functions, to solve this exact problem. >> >> TIA! >> >> -- 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 [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/nodejs?hl=en?hl=en
