On Sunday, July 8, 2012 at 9:15 AM, Vyacheslav Egorov wrote:
> Apparently we define 'stable' differently. > > Probably not, but I think you've misunderstood the --harmony flag and while doing so, you've decided to argue with me about it. > It is behind the flag because it is from the next non-finalized JS standard, > > Yes, I know, I'm _very_ familiar with "the next non-finalized JS standard". > not because it is crashy or buggy. > > Actually, this is _exactly_ what it's for; Map and Set are missing their iterator APIs completely, ES module syntax support appears and disappears (when it is available, module identifiers are assigned as undefined), let is only allowed with the "use strict" prologue... There's more and I think we both agree that these issues are "unstable" and "buggy". > As for string keys: I thought you are proposing to use weakmap like that > here, sorry I misunderstood. > > To clarify, I meant that each scope object could be added as a key to a WeakMap with the cache object as it's value instead of the object dance it does now - which would avoid hasOwnProperty checks and object reference leaks. > Implementation has no problem with them (so nothing to report) but primitives > can be shared in unexpected ways (e.g. two objects with the property foo hold > the same instance of string 'foo'.) Strings don't hold any shared references in JavaScript, but I'm interested in seeing the code you're describing. > so one should always keep that in mind, because value will never be released > if key is strongly reachable. Yes, this is exactly the point of a WeakMap Rick > Vyacheslav Egorov > On Jul 8, 2012 2:53 PM, "Rick Waldron" <[email protected] > (mailto:[email protected])> wrote: > > > > > > On Sunday, July 8, 2012 at 6:05 AM, Vyacheslav Egorov wrote: > > > > > WeakMap/Map/Set are available in V8 for quite some time. You just need to > > > run with --harmony. > > > > > > > > > > > > > > > I'm not sure I understand what the point your trying to make is. I said > > "stable v8" which is meant to imply "not behind a flag". If there are "hard > > to explain memory leaks", that's a bug and should be reported. > > > > Why would you use a WeakMap for use case that required strings as keys? > > This is like using a chainsaw to cut bread. > > > > Rick > > > > > (Though storing anything in a WeakMap with a string key might lead to a > > > hard to explain memory leaks). > > > Vyacheslav Egorov > > > On Jul 7, 2012 6:28 PM, "Rick Waldron" <[email protected] > > > (mailto:[email protected])> wrote: > > > > > > > > > > > > > > > > On Saturday, July 7, 2012 at 10:28 AM, Mariusz Nowak wrote: > > > > > > > > > This is the use case we were missing, you want to do same thing I've > > > > > once tried to do in domjs https://github.com/medikoo/domjs > > > > > Currently I think there's no better solution than polluting global > > > > > scope. > > > > > In domjs I resolved it by introducing dynamic scope ( > > > > > https://github.com/medikoo/domjs/blob/master/lib/dscope.js ). > > > > > > > > > > > > > > > > > > > > > > > > > > > This is a good use case for WeakMaps; they aren't available in v8 > > > > stable yet, but would eliminate the leaky references that could be held > > > > in the current implementation. > > > > > > > > Rick > > > > > > > > > > > > > > > > > but it's not great approach as variable assignments live only during > > > > > function execution, and that's confusing. I think best solution would > > > > > to be have possibility to run modules in some predefined lexical > > > > > scope, but it's not that easy to achieve. > > > > > > > > > > On Saturday, July 7, 2012 3:55:26 PM UTC+2, ajlopez wrote: > > > > > > Thanks! > > > > > > > > > > > > I usually do in your suggested way, and I'm with you. But in this > > > > > > special case, I feel the user of my module could find a bit weird > > > > > > to write > > > > > > > > > > > > var st = require('simpletags'); > > > > > > > > > > > > st.html(st.head(st.title('...')), st.body(st.h1(....)) > > > > > > > > > > > > instead > > > > > > > > > > > > html(head(title('....')), body(h1('...')) > > > > > > > > > > > > in a controlled way (only in its own module). I want to give > > > > > > him/her an option. Ruby has it (as an option, too). It's the first > > > > > > time I found I needed it in Node.js. Usually, I assert "Ruby > > > > > > ceremony > Javascript/Node.js ceremony", but now, I was trapped by > > > > > > this issue. > > > > > > > > > > > > My best solutions: > > > > > > > > > > > > a) > > > > > > var st = require(...); // and use with st.h1, st.h2... > > > > > > > > > > > > b) > > > > > > require('simpletags').exportsTo(global); // maybe in browser I > > > > > > could export to windows directly in the module > > > > > > > > > > > > c) > > > > > > var simpletags = require('simpletags'); > > > > > > eval(simpletags.exportLocalCode()); // where .exportLocalCode > > > > > > returns a String with "var h1 = simpletags.h1; ... " > > > > > > c2) > > > > > > var st = require('simpletags'); > > > > > > eval(st.exportLocalCode('st')); // the local variable name 'st' > > > > > > should be informed to be used in var ...= .... string result > > > > > > > > > > > > On Sat, Jul 7, 2012 at 10:38 AM, Mariusz Nowak <[email protected] > > > > > > (mailto:[email protected])> wrote: > > > > > > > In modules you can achieve the same by assigning function to > > > > > > > global: e.g. `global.foo = function () { .. }` it will work same > > > > > > > as `this.foo = function () { ... }` in REPL. but I would strongly > > > > > > > discourage this, relying on global scope is bad practice. > > > > > > > > > > > > > > I'd say that unless you're using regular require/export logic to > > > > > > > share objects between modules, you're doing something wrong. Try > > > > > > > to think just with require/exports and then you should quickly > > > > > > > find way home. See how module relations in other packages work. > > > > > > > > > > > > > > -- > > > > > > > Mariusz Nowak > > > > > > > https://github.com/medikoo > > > > > > > http://twitter.com/medikoo > > > > > > > > > > > > > > > > > > > > > On Saturday, July 7, 2012 3:18:51 PM UTC+2, ajlopez wrote: > > > > > > > > Thanks for the suggestion!.... but... I missing some part of > > > > > > > > your answer. > > > > > > > > > > > > > > > > I guess I understand the difference btw global, this.property, > > > > > > > > and var local. And then, I understand why it not works. What I > > > > > > > > don't understand is how to circumvent/solve the problem. I > > > > > > > > don't know if your answer is: > > > > > > > > > > > > > > > > a- " you'll get the answers :) " and then, you will know that > > > > > > > > it's impossible to solve, or too weird > > > > > > > > b- you'll get the answers :) " and it's possible in this > > > > > > > > (simple) way.....etc... > > > > > > > > > > > > > > > > AFAIK, it's "a". Am I right? > > > > > > > > > > > > > > > > My problem is: > > > > > > > > > > > > > > > > - module1 requires module2 > > > > > > > > - I want to use the exposed functions of module2 as they were > > > > > > > > defined in module1, using dynamic names. That is, it's not a > > > > > > > > solution > > > > > > > > > > > > > > > > var module2 = require('module2'); > > > > > > > > var Function2 = module2.Function2; > > > > > > > > > > > > > > > > Usually, I did a bit of experiment at REPL. I found that this > > > > > > > > works: > > > > > > > > > > > > > > > > var name = 'Function2'; > > > > > > > > this[name] = ... > > > > > > > > > > > > > > > > var obj = new Function2(); // without using this > > > > > > > > > > > > > > > > BUT it's only works at REPL. So, encouraged by this discovery > > > > > > > > (I expected it will not work), I hoped to make it works in > > > > > > > > other context. > > > > > > > > > > > > > > > > Now, I understand why it is work in REPL. Notably, in REPL > > > > > > > > > > > > > > > > this == global > > > > > > > > > > > > > > > > so it's possible to emulate > > > > > > > > > > > > > > > > var foo = ... > > > > > > > > > > > > > > > > with something like (pseudocode) > > > > > > > > > > > > > > > > name = 'foo' > > > > > > > > var [name] = ..... > > > > > > > > > > > > > > > > writing > > > > > > > > > > > > > > > > name = 'foo'; > > > > > > > > this[name] = ... > > > > > > > > > > > > > > > > and then foo is available "as if it is" a local var. > > > > > > > > > > > > > > > > But inside a running .js, this is not equal to global. I was > > > > > > > > tricked by REPL ;-) > > > > > > > > > > > > > > > > So, the better solution I found so far is to put something like > > > > > > > > this in module1: > > > > > > > > // > > > > > > > > http://stackoverflow.com/questions/5625569/include-external-js-file-in-node-js-app > > > > > > > > > > > > > > > > > > > > > > > > var fs = require('fs'); > > > > > > > > var vm = require('vm'); > > > > > > > > > > > > > > > > var includeInThisContext = function(path) { > > > > > > > > var code = fs.readFileSync(path); > > > > > > > > vm.runInThisContext(code, path); > > > > > > > > }.bind(this); > > > > > > > > > > > > > > > > includeInThisContext(__dirname + '/module2.js'); > > > > > > > > > > > > > > > > console.log(foo); // it's defined > > > > > > > > > > > > > > > > where module2 define foo: > > > > > > > > > > > > > > > > foo = {}; > > > > > > > > > > > > > > > > BUT IN MY CASE, module2 doesn't define the functions at its own > > > > > > > > context: > > > > > > > > https://github.com/ajlopez/SimpleTags/blob/master/lib/simpletags.js > > > > > > > > > > > > > > > > it uses an array to dynamically define and export functions. I > > > > > > > > never have > > > > > > > > > > > > > > > > function h1() { > > > > > > > > } > > > > > > > > > > > > > > > > function h2() { > > > > > > > > } > > > > > > > > > > > > > > > > defined at module2 context. And I don't want this. My DSL > > > > > > > > defines a function for each HTML tag. > > > > > > > > > > > > > > > > Now, I want to have these dynamically defined functions from > > > > > > > > module2 accessible in outer module1, as they were local to it. > > > > > > > > > > > > > > > > I could write inside my module, > > > > > > > > > > > > > > > > var h1 = makeTag('h1'); > > > > > > > > var h2 = makeTag('h2"); > > > > > > > > ... > > > > > > > > .... > > > > > > > > > > > > > > > > for dozens of tags, and then use something like > > > > > > > > includeInThisContext.... but I feel it's too weird. > > > > > > > > > > > > > > > > Apparently, my problem is: I didn't find a way to define a > > > > > > > > local var with a dynamic name. > > > > > > > > > > > > > > > > The original DSL in Ruby: > > > > > > > > https://github.com/dlitvakb/deklarativna/blob/master/test/test_deklarativna.rb > > > > > > > > > > > > > > > > > > > > > > > > use "include dslmodule". And inside the dsl module, it defines > > > > > > > > dynamically named functions at module top level. So the > > > > > > > > functions are automatically available to the module that makes > > > > > > > > the includes. > > > > > > > > > > > > > > > > That is the "trick" I didn't found how to emulate in > > > > > > > > Node.js/require/CommonJS world. > > > > > > > > > > > > > > > > Some links in my research: > > > > > > > > http://stackoverflow.com/questions/5833978/javascript-how-to-use-dynamic-local-variables > > > > > > > > > > > > > > > > http://stackoverflow.com/questions/5094862/how-do-i-access-a-local-variable-dynamically-via-a-string-form-of-its-name-fro > > > > > > > > > > > > > > > > http://stackoverflow.com/questions/598878/how-can-i-access-local-scope-dynamically-in-javascript > > > > > > > > > > > > > > > > http://stackoverflow.com/questions/2336508/javascript-get-access-to-local-variable-or-variable-in-closure-by-its-name > > > > > > > > > > > > > > > > http://stackoverflow.com/questions/1119335/javascript-local-variable-declare > > > > > > > > > > > > > > > > > > > > > > > > The better approach I found in these links is to use eval > > > > > > > > (!!??): > > > > > > > > eval("var "+name+ " = ...."); > > > > > > > > > > > > > > > > Am I right? the only ways are the above ones? Or is another > > > > > > > > way? > > > > > > > > > > > > > > > > Any suggestions? > > > > > > > > > > > > > > > > Angel "Java" Lopez > > > > > > > > > > > > > > > > > > > > > > > > On Sat, Jul 7, 2012 at 9:27 AM, Mariusz Nowak > > > > > > > > <[email protected] (mailto:[email protected])> wrote: > > > > > > > > > @ajlopez get to know how variable scoping in JavaScript works > > > > > > > > > (what is global, how this and how local variable works), and > > > > > > > > > you'll get the answers :) > > > > > > > > > > > > > > > > > > > > > > > > > > > On Saturday, July 7, 2012 2:11:56 PM UTC+2, ajlopez wrote: > > > > > > > > > > Hi people! > > > > > > > > > > > > > > > > > > > > A very simple question. When I write in the Node repl: > > > > > > > > > > > > > > > > > > > > this.foo = 'bar'; > > > > > > > > > > console.log(foo); > > > > > > > > > > > > > > > > > > > > it's ok, foo is defined. But writing that code in file.js > > > > > > > > > > and running > > > > > > > > > > > > > > > > > > > > node file.js > > > > > > > > > > > > > > > > > > > > then foo is not defined. > > > > > > > > > > > > > > > > > > > > Or require('file.js'), then foo is not defined. > > > > > > > > > > > > > > > > > > > > Any way to define a variable in the "current context"? > > > > > > > > > > Apparently, "this" properties and "current context" top > > > > > > > > > > variables are the same in REPL, but they are not the same > > > > > > > > > > in .js, or inside a required module. > > > > > > > > > > > > > > > > > > > > I want to do this in a dynamic way: > > > > > > > > > > > > > > > > > > > > name = 'foo'; > > > > > > > > > > // ... > > > > > > > > > > this[name] = 'bar'; > > > > > > > > > > > > > > > > > > > > so > > > > > > > > > > > > > > > > > > > > foo = 'bar'; > > > > > > > > > > > > > > > > > > > > is not a solution in my context. > > > > > > > > > > > > > > > > > > > > I could use: > > > > > > > > > > > > > > > > > > > > global[name] = 'bar'; > > > > > > > > > > > > > > > > > > > > but I want to expose the new "current context" top > > > > > > > > > > variables only in my "current context" without pollute the > > > > > > > > > > global environment. > > > > > > > > > > > > > > > > > > > > I encountered this problem when coding a simple HTML DSL: > > > > > > > > > > https://github.com/ajlopez/SimpleTags/blob/master/test/exportsTo.js > > > > > > > > > > > > > > > > > > > > I want the DSL functions to be accesible as: > > > > > > > > > > > > > > > > > > > > require('simpletags').exportsTo(????); // ???? == global? > > > > > > > > > > this? Now, I should use global to make it works in any > > > > > > > > > > situation > > > > > > > > > > > > > > > > > > > > then, use the exported function as functions in current > > > > > > > > > > context: > > > > > > > > > > > > > > > > > > > > html(body(h1("TheNextBigThing"))); > > > > > > > > > > instead > > > > > > > > > > > > > > > > > > > > var st = require("simpletags"); > > > > > > > > > > > > > > > > > > > > st.html(st.body(st.h1("TheNextBigThing"))); > > > > > > > > > > > > > > > > > > > > Any other way? > > > > > > > > > > > > > > > > > > > > TIA > > > > > > > > > > > > > > > > > > > > Angel "Java" Lopez > > > > > > > > > > http://ajlopez.wordpress.com > > > > > > > > > > @ajlopez > > > > > > > > > > gh:ajlopez > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > Job Board: http://jobs.nodejs.org/ > > > > > > > > > Posting guidelines: > > > > > > > > > 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