binding to a builtin name fails cryptically

[dagitses]

Example:
<template repeat="{{dir in [1, 2, 3]}}">{{dir}}</template> => 333

I scratched my head on this one for a very long time before I realized that dir() is some kind of special value, at least in Chrome.

Apologies for the imprecision, I don't know the status of "dir" in Javascript, i.e. is it just in Chrome, is it a builtin? Nevertheless, it exhibits this really unfortunate behavior.

Is is possible to detect such uses, or to make them work as intended?

http://jsbin.com/polojite/1/edit

[ebidel]

Sorry, that's definitely a head scratcher. We should probably throw a warning for cases like this.

I believe it's part of the Console API (console.dir): https://developer.chrome.com/devtools/docs/console-api#consoledirobject

[sjmiles]

'dir' specifies directionality ('rtl' or 'auto') for HTMLElement:
https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement.dir

On Tue, May 20, 2014 at 9:17 AM, Eric Bidelman notifications@github.comwrote:

Sorry, that's definitely a head scratcher. We should probably throw a
warning for cases like this.

I believe it's part of the Console API (console.dir):
https://developer.chrome.com/devtools/docs/console-api#consoledirobject

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[ebidel]

Ah yes. Related: #123

[dagitses]

Edit: removed. I may be wrong.

[dagitses]

Removed previous comment, I probably misdiagnosed the issue.

[sjmiles]

This sounds like #123, but it's not. This variable dir should be distinct from any prototype, I believe this is a bug in TemplateBinding. I'm working on a reduction and an issue ticket.

[sjmiles]

Not TemplateBinding, rather polymer-expressions.

[ebidel]

Thanks @sjmiles.

[sjmiles]

googlearchive/polymer-expressions#33

[dagitses]

Thanks for the quick triage.

[sorvell]

Closing since the root cause (googlearchive/polymer-expressions#33) has been fixed.