Re: Reflection on the special telco of CSVW

On 10 Sep 2014, at 13:42 , Dan Brickley <danbri@google.com> wrote:

> On 10 September 2014 12:27, Ivan Herman <ivan@w3.org> wrote:
>> 
>> On 10 Sep 2014, at 12:21 , Andy Seaborne <andy@apache.org> wrote:
>> 
>>> One aspect of this choice is whether a transformation of a CSV file to be published on the web so other people (other than the data publisher) run it?  Or is it the input for a toolkit to generate format X and then a file with format X is put on the web?
>>> 
>>> If transforms are published, then there is a requirement for a programming-language, template-language independent solution.  I agree this is more work.
>> 
>> But the point is that such programming languages already exist. Several of them. One could say that we should not define yet another one.
> 
> I have the feeling that we're talking past each other some of the time
> here. Reading Andy here, my first reading was that requiring a
> "template-language independent" template/transform language seemed
> like a contradiction. But I guess the idea is that we want portability
> between specific template/transform software packages / projects. So
> for example, emphatically blessing something as specific as Django
> just wouldn't make sense for W3C, even though we might want to make it
> possible in metadata for the Django-loving subset of the Web community
> to declare associated templates via JSON-LD metadata.
> 
> The {{ mustache }} -based notations seem to be common enough that they
> transcend any particular software project and programming language.
> But there are some {{ }}-based template systems that slip rather
> casually into assuming full Javascript capabilities, which is
> something we ought to be very wary of doing. There is an interesting
> design space between simple variable interpolation vs turing complete.
> 
> e.g.  http://www.polymer-project.org/docs/polymer/expressions.html
> ("Polymer supports expressions in {{}} with a strict subset of the
> JavaScript language. In order to use this feature, it’s important to
> understand its behavior and limitations: The goal for inline
> expressions is to allow the expression of simple value concepts and
> relationships. It is generally bad practice to put complex logic into
> your HTML (view).").
> 

Right. I do not think any of the features that we discussed around templates (the discussion led by Jeremy or the stripped version I played with) are language specific. And indeed they should not. 


> 
>> If a template format is defined (complex or simple), then one can also publish the templates (e.g. [1,2]).
>> 
>> In other words, I am not sure I understand your point in terms of deciding whether we do templating or not.
>> 
>> [1] https://github.com/w3c/csvw/blob/gh-pages/experiments/simple-templates-jquery/simple_test/test-json.tmpl
>> [2] https://github.com/w3c/csvw/blob/gh-pages/experiments/simple-templates-jquery/simple_test/test-turtle.tmpl
>> 
>> 
>>> 
>>> Assuming javascript is a possibility; while it is arguably the safest single choice, it does not work for many environments.  If you're in a lang-X programmer (e.g. R), you want to use lang-X skills.
>>> 
>>> Otherwise, if it's a tool-input and not published to be run elsewhere, it does not need this portability requirement.  A language or a basic-transform+improve style is more reasonable.  The tool space is weaker (transforms are tool specific).
>>> 
>> 
>> 
>> I do not understand. *If* we define a template language (simple or complex), it can be defined in different languages. I happened to have that done in Javascript, but it could have been done in Python without too much problems.
> 
> Ivan - when you say "it can be defined in different languages", can I
> read "can be implemented" in different languages?

I am sorry. Answering a mail while on a meeting is bad:-) 

s/defined in/implemented in/


> Your implementation
> seemed to be of a mustache-family language that *happened* to be
> implemented in Javascript. I would hope that the same templates could
> equally well be processed by Java, Python etc. implementations, and
> that a group like ours should be capable of writing unit tests to
> probe the behaviour of such implementations.

Absolutely. The core of it is doable in Python (because there is also a Mustache implementation in Python, the necessary effort would not be bigger). I am sure that is the case for other languages, too. And to be very clear: I used an existing Mustache implementation because I am lazy, and did not want to spend time in implementing the {{.}} template management myself; I am not committed to Mustache (and I use a small part of it).

Ivan


> 
> Dan


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Ivan Herman, W3C 
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