Re: [PATCH] Add :noweb-prefix and :noweb-trans babel header arguments

[Sébastien Miquel]

Hi,

Ihor Radchenko writes:

> prin1-to-string is too specific and only solves a single use-case.
>     
    prin1-to-string is actually universal in a
      way, since any other
      manipulation can then be achieved with
      
      : (setq var (do-something <<nw>>))
      
      at least as long as you're tangling to a programming language,
      that
      can read lisp strings.
> Consider the following example:
>
> #+BEGIN_SRC emacs-lisp :noweb yes :tangle yes :noweb-prefix no :noweb-trans prin1-to-string
> <<preamble>>
> (setq latex-header <<nw>>)
> #+END_SRC
>
> There are two noweb references here. Setting source block-wide
> :noweb-trans is not helpful because the first reference will be
> incorrectly filtered through prin1-to-string.
>     
    Indeed. Originally I had thought of adding a
      new syntax <<"nw">> to
      insert a string representation. I've attached a new patch, that
      does
      this instead of introducing :noweb-trans. Now that I think of the
      universality of prin1-to-string, I actually like it slightly
      better
      than :noweb-trans. It would break existing "nw"-like noweb
      references.
      
      Of course, one can work around this easily enough by using two
      blocks.
> I'd rather introduce a new syntax to transform the noweb reference
> inline. Something like
>
> #+BEGIN_SRC emacs-lisp :noweb yes :tangle yes :noweb-prefix no
> <<preamble>>
> (setq latex-header <<(prin1-to-string nw)>>)
> #+END_SRC
>     
    You'd need to only allow a single function
      call with only one
      argument, or use something like <<(prin1-to-string
      <<nw>>)>>. The
      change would be much more complex than what I propose, for maybe
      little benefit.
> > [...]
> >       
> This sounds a bit confusing. I would also add an example where it is
> useful to set :noweb-prefix to no.
>

I've added such an example in the revised patch attached.

Thanks for the feedback.

Regards,

-- 
Sébastien Miquel

0001-ob-core.el-Add-noweb-prefix-noweb-trans-babel-header.patch
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0001-ob-core.el-noweb-prefix-header-argument-and-nw-synta.patch
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