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]> 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<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
>>>
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