[Docutils-develop] Enhancement: Make the parser obey custom roles

[Marcello P. <mar...@pe...>]

This is one extension we implemented at Project Gutenberg.

Rationale:

In some books emphasis is not rendered as italics, eg. in old German 
books emphasis is rendered as g e s p e r r t.

We want to be able to redefine the role :emphasis: so as to render in 
gesperrt. Like this::

    .. role:: emphasis(emphasis)
       :class: gesperrt

But in the current implementation the custom role above works only if we 
write :emphasis:`this`. That is awkward.

We want to be able to still write *this* and have the custom role to 
take effect.


Implementation:

We explored this by providing our own Inliner and overriding the 
inline_obj method. (Proof of concept code is available.) This takes care 
of emphasis, strong and literal, but doesn't work with all inlined 
elements. Also, if you override the default role, you have to redeclare 
it to clear the role cache.


I think this functionality should go into the core and the parser should 
go through the role system for all inlined elements.


Comments?


-- 
Marcello Perathoner
web...@gu...