Allow helpers to return primitives

[sethkinast]

Previously returning a primitive would crash rendering with no way to recover.
Primitives are always HTML-escaped with no way to turn that off unless you override with a filters param. If you need to adjust the escaping, you need to return a Chunk and do the work yourself.

Closes #645

[smfoote]

Looks good. My only question is, what is the difference between this.await and chunk.await?

[sethkinast]

At the top of the function chunk gets aliased to this.

On Tue, Apr 28, 2015, 9:18 AM Steven notifications@github.com wrote:

Looks good. My only question is, what is the difference between this.await
and chunk.await?

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Reply to this email directly or view it on GitHub
#647 (comment).

[smfoote]

Got it. Thanks.

[prashn64]

Let's have this accept a filters param from the helper and pass it to chunk.reference. 'h' will still be the default though.

Otherwise, looks good!

[sethkinast]

I really like this. Thanks for the idea!

[jimmyhchan]

I know this isn't going to be easy but we should support pragmas and not hardcode the h here.

e.g.

{%esc:s}
  {@unsafe}{~n}
  {%esc:h}
    {@unsafe}
  {/esc}
{/esc}

[sethkinast]

Super legit, let me dive into that.

[sethkinast]

Thanks for the great catch. Test cases added.

[sethkinast]

To clarify from discussion offline with Jimmy:

Currently you can write a context helper that does this:

"url": function(chunk, context) {
  return 'http://' + context.get('url'); // safe
}

But you can't write a helper that does the same thing:

dust.helpers.addHTTP = function(chunk, context, bodies, params) {
  return 'http://' + context.get('url'); // Exception!
  return chunk.write('http://' + context.get('url')); // Evil! params.value is not escaped
};

So this is just intended to normalize these.

[sethkinast]

As discussed in the WTF I've removed support for a filters param; we can maybe revisit it later.

So the new capability is only to normalize the behavior of global helpers and context helpers.

[sethkinast]

Hahaha @jimmyhchan

I read the code for chunk.reference and look what it already does:

{foo|js|s}

function() {
  var d = 1;
  return {
    foo: function(chunk, context, bodies, params) {
      chunk.write(JSON.stringify(params));
    }
  };
}

{"auto":"h","filters":["h"]}

Dust already automatically passes auto and filters as params, so they are already reserved! That makes me feel a lot better about actually formalizing that for helpers...