Re: experimental features in Bison 2.3a+

[Hans Aberg]

On 2 Dec 2006, at 06:23, Paul Eggert wrote:

> > 2. The prologue alternatives: %code, %requires, %provides, and % 
> > code-top.
>
> Yes.  Though to be honest I can't even remember what all of them are
> for....

I have looked this up in the Bison manual CVS version. The idea I had  
a couple of years ago, in order to avoid such a cluster of options  
nobody can recall, was to have just one command with the syntax:
  %code <identifier> {<code>}
With this method, people developing skeleton files need not asking  
for a Bison grammar tweak. As I pointed out before, it is probably  
better to use %define for writing verbatim macros, and %code for code  
that adjusts according to output language.

Then the variations %requires, %provides, and %code-top might get  
uses such as
  %code header {<code>}      - For C++ (replacing %requires)
  %code import {<code>}      - For Java (replacing %requires)
  %code source-top {<code>}  - Replacing %code-top
or whatever: one can use the old names "requires", "provides", "code- 
top", too; whatever one finds is intuitive and descriptive.

It is still possible to extend the current %code by just letting it  
having an optional argument.

  Hans Aberg