Workaround for escaping annotations with “square-brace” / “curly-brace” syntax

[leogr]

Issue
Assume you need to set the literal value [[WIP]] to an element's property (or an attribute).

Due to the "square-brace" syntax ([[]]), the following code does not work:

<my-element title="[[WIP]]"></my-element>

The reason is that the annotation parser treats [[WIP]] as an annotation for data binding.

Currently, I have not found any documented way to escape the “square-brace” / “curly-brace” syntax. I just found this TODO:

    // TODO(kschaaf): We could modify this to allow an escape mechanism by
    // looking for the escape sequence in each of the matches and converting
    // the part back to a literal type, and then bailing if only literals
    // were found
    _parseBindings: function(text) {

Use cases
Escaping annotation can be very useful when you work with server-side generated HTML, or when you need to pass a JSON serialised string, for example:

<my-element values='{"foo":"{{baz}}"}'></my-element>

Workaround
But I found a working workaround doing so:

<my-element title="[[serialize('[[WIP]]')]]"></my-element>

It works because template has the serialize method that does nothing when the input is a String, as documented here, and so the first passed param is returned untouched.

Questions
I don't think that it's a definitive solution but I would like to know:

• Is it an acceptable way to escape the annotation syntax?
• Is there a better way to escape the annotations?
• Or will it be available in next release?

Currently, I'm just trying to understand which is the best approach for this use case.

I used the [[..]] syntax as example, but it works for {{..}} too
This workaround could also work for googlearchive/TemplateBinding#186

[leogr]

The #3529 could be a definitive solution

[TimvdLippe]

@leogr was correct that that PR was intended to implement this. However, we decided to not configure this globally. Rather you can implemented this functionality yourself in _parseBindings. For more info see #3529 (comment)