Global and deep stack context functions have wrong 'this' pointer.

[wshaver]

Related to: #96 (20 days previous to this post)

The fix in this pull request always uses the 'current context'

elem = elem.apply(context.current(), [this, context, null, {auto: auto, filters: filters}]);

The testing framework doesn't allow for more complicated contexts to be easily defined as it expects a simple single-stack context. Consider the following more complicated context and global stack:

var context = dust.makeBase({
 name: '1Bob',
 getName1: function(){ return this.name;}});
var instance = context.push({
 name: '2Joe',
 getName2: function(){ return this.name;}});
instance = instance.push({
 name: '3Tim',
 getName3: function(){ return this.name;}});

With the dust template:

{getName1}
{getName2}
{getName3}

The current implementation returns:
3Bob3Bob3Bob

Please indicate where and how to put a test with a more complicated context and I'll be happy to add one.

To solve this issue, we need to bind the function at compile time. Using underscore (just to get it done quickly) the code looks like this:

Context.prototype.get = function(key) {
  var ctx = this.stack, value;
  while(ctx) {
    if (ctx.isObject) {
      value = ctx.head[key];
      if(typeof value === 'function'){
        value = _.bind(value, ctx.head);
      }
      if (value !== undefined) {
        return value;
      }
    }
    ctx = ctx.tail;
  }
  if(this.global){
    value = this.global[key];
    if(typeof value === 'function'){
      value = _.bind(value, this.global);
    }
    return value;
  }
  return undefined;
};

This fixes the global / deep stack issue and passes the unit tests defined in pull request 96. I've implemented a minimal 'bind' inside of the .git function to avoid the use of underscore. Please tell me where to add tests for this issue. I've added some manual tests in a site I'm building, but would like to add tests in the linkedin project.

[travisbot]

This pull request passes (merged a69332c into d0affe6).

[vybs]

in the process of reviewing. thanks @wshaver

[wshaver]

https://github.com/wshaver/speck This is some requirejs + dustjs + backbone glue I wrote. I turns the backbone view into the global context for the dustjs snippet, so that the snippets can call members of the view. (With this patch anyway.)

[vybs]

@wshaver Sorry for the delay, but overall + 1 on the idea and also thanks for bringing this up.

Are you still looking for pointers to add tests?

Adding a complex context is no different than here
https://github.com/linkedin/dustjs/blob/master/test/jasmine-test/spec/grammarTests.js

[wshaver]

Is this the file I should add tests to for this issue?

[vybs]

can we move this out of get?

[wshaver]

Where would you like it?

[vybs]

one more q:
would not the following need the same check?

Context.prototype.getBlock = function(key, chk, ctx) {
if (typeof key === "function") {
key = key(chk, ctx).data;
chk.data = "";
}

dynamic partials

if (typeof elem === "function") {
return this.capture(elem, context, function(name, chunk) {
dust.load(name, chunk, context).end();
});

[wshaver]

It might, I'll try and add a test for both.

[wshaver]

Can you provide an example of a partial that includes a function? I'll work on this some more tomorrow - nap time.

[vybs]

sure :) thanks for your help.

I was hinting at the dynamic partials, {">partial{name}":overridecontext/} and the context itself been a function. I have not personally used this ( but the code supports it )

[wshaver]

So where did you want the bind function?

[wshaver]

Also I haven't ever used dynamic partials, and therefore my ability to write a test for them is minimal. As long as this code isn't breaking any existing tests, to do we need more tests? Can't someone using d-partials submit a bug if they're not working?

[vybs]

you can also create a new one if need be, since its been a plan to refactor the grammar and dust-core tests out.

[wshaver]

How do I create a global context inside grammarTests.js? That's what I was not sure about before.

[vybs]

Ah, to simulate global context,

may be extend the to have a globalContext, just like we have context in the specs

[wshaver]

Actually we can do it by changing the order of the includes in the specRunner. Then you can have a test like:

  {
    name:     "test that deep stack functions have the correct scope",
    source:   "{getName1}{getName2}{getName3}",
    context:  (function(){
                var context = dust.makeBase({
                  name: '1Bob',
                  getName1: function(){ return this.name;}
                });
                var instance = context.push({
                  name: '2Joe',
                  getName2: function(){ return this.name;}
                });
                instance = instance.push({
                  name: '3Tim',
                  getName3: function(){ return this.name;}
                });
                return instance;
              }()),
    expected: "1Bob2Joe3Tim",
    message: "Should allow for deep stack functions"
  }

[vybs]

another note: in order to distinguish between the dust compiler created functions and the lambda's that can exist as part of the context , we have
the elem.isFunction check

see the tap method fyi

[wshaver]

I'm not quite sure what you're saying here. The value here is likely outside of dust as it can be part of the 'context'.

[vybs]

@wshaver do let me know when this is good to be reviewed.

[vybs]

ping? @wshaver

[wshaver]

Hey there, sorry I've been busy with other projects. I've dumped my fork and rebuilt it. Should I issue a separate pull request?

[vybs]

Welcome back ! sure with the changes we talked about:)

[wshaver]

I asked a couple of other comments above clarifying the changes you want.

[vybs]

closed, since it is unclear if this is a priority to fix.