Investigate using private vars for _view handling in #each helper about thorax HOT 11 CLOSED

@candid @kpdecker I wasn't aware of the existence of private vars until very recently. Is there any documentation on them at all? Can't find anything on the handlebars website other than a single mention of @index. No objection to using them instead of an actual variable, will try it out.

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@kpdecker, ran into a bit of a bummer, which is that helpers don't receive data downstream from each / with. I wrote a failing test case:

https://github.com/eastridge/handlebars.js/commit/7ce13a3c2c0dce9a00a5b569f41fa6361d281312

Is this the expected behavior? If it is the private variable solution won't work for us. If it isn't I'll see if I can make a fix.

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Add data: true to the compiler or reference one of the @ vars in the template. Does it still fail?

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Adding a @ var in the template does make it show up in the context, but we want it to be available wether or not it's actually declared in the template. Is this desired behavior? Also, what flag would I set on the compiler? Not setting anything now but would need to be something that is both available in precompiling mode and via Handlebars.compile.

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A pull request to fix the issue has been opened here:

handlebars-lang/handlebars.js#390

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A branch implementing this is here:

https://github.com/walmartlabs/thorax/tree/private-vars

We need the pull request on wycats/handlebars.js to get merged for this to proceed as requiring {data: true} to be passed to Handlebars.compile is a recipe for trouble. If the pull request is rejected (lil help @kpdecker ;) we can revisit wether we want to impose this requirement.

Also seems like the {{cid}} var should move to be a private var. @candid @jhudson8 are there any other useful always available private vars you guys have wanted available?

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My experience with private vars is limited to a few hours of dealing with @Index. I will let you know if I run into other cases where they would be helpful.

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@eastridge I think the cid is a good candiate to move over.

On the upstream default can we detect when data isn't provided in a particular template and warn? Can you create a PR for the private-var branch?

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@kpdecker Ok, hopefully we can get some traction on handlebars-lang/handlebars.js#390 but if not I think throwing an error is a good stopgap. Can you make the needed change in lumbar, or is it a config option I can pass somewhere?

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@kpdecker @candid, closing this ticket, check out:

#73

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@eastridge adding "data": true to the precompile config section in lumbar should do the trick. I'll update the shared lib for this.

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