webgen users - Mar 2007 - Transformation order

I see that the well-defined order for transforming a page to HTML is:
- Transform the content using the content converter
...
- Replace tags

I think it should be the other way around.

I wrote this plugin that transform

    {flickr: <url of the photo>}

into something like:

    <div> Foto, caption, etc. </div>


Now, because of the order of transformations, the content-converter
(bluecloth or maruku) will first transform the tag in:

     <p>{flickr: <url of the photo>}</p>

and then the tag processor will transform this in

    <p><div> Foto, caption, etc. </div></p>


So, two questions:
1 - is possible to customize the order of transformations?
2 - I was wondering why did you set this order instead of the other
way around: was there a reason, or was it a random decision? I think
that the other order is much more intuitive.


-- 
Andrea Censi
      "Life is too important to be taken seriously" (Oscar Wilde)
Web: http://www.dis.uniroma1.it/~censi

On 09.03.2007, at 21:40, Andrea Censi wrote:
> I see that the well-defined order for transforming a page to HTML is:
> - Transform the content using the content converter
> ...
> - Replace tags
>
> I think it should be the other way around.
>
> I wrote this plugin that transform
>
>     {flickr: <url of the photo>}
>
> into something like:
>
>     <div> Foto, caption, etc. </div>
>
>
> Now, because of the order of transformations, the content-converter
> (bluecloth or maruku) will first transform the tag in:
>
>      <p>{flickr: <url of the photo>}</p>
>
> and then the tag processor will transform this in
>
>     <p><div> Foto, caption, etc. </div></p>
>
>
> So, two questions:
> 1 - is possible to customize the order of transformations?
> 2 - I was wondering why did you set this order instead of the other
> way around: was there a reason, or was it a random decision? I think
> that the other order is much more intuitive.
There are always trade-offs involved. I thought long about the pros  
and cons of the current transformation order. Some reasons I chose  
this one:

* The tag plugins know what to output, namely pure HTML. If  
converting a page file to HTML after replacing tags, it depends on  
the content converter to the right thing with the embedded HTML. If  
the page file is converted to HTML first, replacing the tags with  
pure HTML is easy. Same is true for ERB output.

* And generally: after reading a page file, it is automatically  
converted to HTML. Therefore all plugins working with the page file  
can be assured that can work on HTML.

* The in-page menu only works because of this ordering. After reading  
in a page file, it is converted to HTML and then all header elementes  
h1, h2, ... with id="..." are searched for and fragment nodes for  
each such element are generated. This would not be possible without  
transforming the page to HTML.

I know that this transformation order is not perfect but it turned  
out to be the best viable solution for me. However, I''m open for  
other/better suggestions concerning the transformation pipeline. One  
major reason for choosing this particular order was the ability to  
use in-page menus afterwards and this should be possible with another  
order, too!

Currently it is not possible to customize the order of  
transformations. Maybe this will be possible in the next bigger  
release (0.5.0 - which is also worked on already, more to that later  
on webgen-users). Your problem with the additional <p>...</p> tags  
can be overcome, for example with Textile markup, by specifying that  
some parts should not be formatted by Textile using the  
<notextile>...</notextile> tags. I don''t know if something
like this
exists for Markdown or Maruku.

Bye,
   Thomas

> There are always trade-offs involved.
Of course.
> Currently it is not possible to customize the order of
> transformations.
Or, maybe a little less: give each processor a flag that tell webgen
to run it before or after the content converter.
> Maybe this will be possible in the next bigger
> release
... which includes extensive blogging support?


-- 
Andrea Censi
      "Life is too important to be taken seriously" (Oscar Wilde)
Web: http://www.dis.uniroma1.it/~censi

On 11.03.2007, at 14:29, Andrea Censi wrote:
>> There are always trade-offs involved.
>
> Of course.
>
>> Currently it is not possible to customize the order of
>> transformations.
>
> Or, maybe a little less: give each processor a flag that tell webgen
> to run it before or after the content converter.
>
>> Maybe this will be possible in the next bigger
>> release
>
> ... which includes extensive blogging support?
There is already a plugin in the feature request tracker (created by  
Fritz Heinrichmeyer) which provides blogging and rss support  
(although for webgen 0.3.8). Based on this and comments of other  
people I have taken notes so as to what one would expect from such a  
plugin and when I have enough time I will post them to this mailing  
list for further discussion!

Bye,
   Thomas