Re: [mustache] The docs

From: Andrzej Krzemienski (akrzemi1_at_[hidden])
Date: 2023-02-07 16:26:05

wt., 7 lut 2023 o 16:00 Peter Dimov via Boost <boost_at_[hidden]>
napisał(a):

> Andrzej Krzemienski wrote:
> > Hi Everyone,
> >
> > I wanted to share my initial thoughts after reading the docs for the
> proposed
> > Boost.Mustache.
> >
> > If some library docs said "I am implementing JSON", I more-less know
> what to
> > expect, because JSON is popular, I used it, so one can reliably predict
> what the
> > library delivers.
> >
> > This is not the case with Mustache. It is the first time I have heard
> this name.
> > Apparently, it is a less popular thing. Therefore, I would expect some
> more
> > introduction than just an external link.
>
> You are right, the MVP in this case turned out to be too M. I should add a
> documentation section that describes the Mustache syntax.
>
> > The linked page also doesn't contain
> > sufficient information  but further links. For instance to
> > https://mustache.github.io/mustache.5.html, but this information also
> doesn't
> > help me find answers to my questions:
> >
> > 1. What is considered an "optional part" of mustache? Boost.Mustache
> says it
> > only implements the non-optional parts, but docs in mustache(5) do not
> > indicate the optional parts.
>
> These are described here: https://github.com/mustache/spec

Thanks.

>
>
> > 2. It is clear to me that the procedure takes a template (with
> mustaches) and
> > the data to be replaced. But what is the range of the acceptable formats
> of this
> > data? The examples show that it is JSON, but does it have to be JSON?
> > Boost.Mustache docs say it could be 'described' classes? But is that
> all? How
> > about Boost.PropertyTree? What does the specification for Mustache say
> > about it?
>
> At the moment the supported data sources are json::value and types
> convertible to json::value via json::value_from. What these types are is
> explained here:
>
>
> https://www.boost.org/doc/libs/1_81_0/libs/json/doc/html/json/conversion.html

Ok, so this explains what Boost.Mustache does today. But on a higher level,
does the *specification* for mustache templates require that data is in the
JSON format? The examples in the web show JSON as the source of data.
Boost.Mustache says about everything convertible to json::value.
It looks like the JSON input is a must. But I can see no formal
specification for this. In fact, is there a one "source of truth" about
mustache templates?

>
> > 3. I do not see any specification (neither in Boost.Mustache docc, nor
> in the
> > linked  mustache(5)) for what is the required behavior when I have nested
> > mustashes with the same name, or a JSON file with nested elements of the
> > same name.
>
> I'm not sure I understand this question. Do you mean things like
>
> {{#foo}}
>   {{#foo}}
>     {{foo}}
>   {{/foo}}
> {{/foo}}
>
> ?
>
> If so, the way this works is that every element of data["foo"] is pushed to
> the top of the so-called "context stack", where entities are looked up. If
> this element itself contains a member "foo", this member will be used for
> the nested {{#foo}}. (If not, the parent "foo" will be used.)
>

This is what I would expect. And apparently you also. But are you
explaining your implementation or the "formal specification" of mustache
templates?

Regards,
&rzej;

>
>
>
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