Re: Macros [was: Re: ATTR_HTML for a clickable image, howto?]

["Sebastien Vauban" <wxhgmqzgwmuf-geNee64TY+gS+FvcfC7Uqw@public.gmane.org>]

Hi Nicolas,

Nicolas Goaziou wrote:
> Bastien <bzg-mXXj517/zsQ@public.gmane.org> writes:
>> François Pinard <pinard-CRDzTM1onBSWkKpYnGOUKg@public.gmane.org> writes:
>>> If macros are there to stay in Org, it might be worth documenting a more
>>> complete specification about how to define and use them.
>>
>> I'd welcome some improvement of the manual wrt macros -- any taker?
>
> Before documenting anything, we should first define them clearly.

I think you're right here, seen the latest threads on this.

> That is, we can define them through documentation, but we shouldn't write
> documentation by looking at their current implementation.
>
> Should macros be allowed anywhere (which means that the user can shoot
> himself in the foot) or should their expansion happen in a protected
> environment (thus limiting their power)?

If I had to choose, I would opt for the first case...

> In the first case, can macros generate inline Babel code, that will be
> executed before export?

... where macros would be pre-processed "à la M4" (or C preprocessing):
replacing some keyword with some other expression.

> In the second case, what types of elements are allowed in the protected
> environment?
>
> Also, do we want to allow multiples macros definitions to stack up? I.e.
>
>   #+MACRO: a-macro First line of the macro.
>   #+MACRO: a-macro Second line of the macro.
>
> If so, do we allow blank lines in them, meaning they can break document
> structure even more?
>
> Can the macros be nested?
>
> Since macros arguments are comma-separated, how do one insert commas
> within an argument?
>
> Are newline characters allowed in arguments? If not, what else is
> forbidden there?
>
> There are probably other questions, but it should be a good start for
> a correct implementation.

An extra question is: the "replacing expression" of a macro, must it be pure
text, or can it be anything (such as code that will be interpreted, in a
further pass, by some back-end)?

Best regards,
  Seb

-- 
Sebastien Vauban