Re: %name-prefix overrides --name-prefix?

[Hans Aberg]

On 14 Dec 2006, at 21:08, Joel E. Denny wrote:
> > One may just go in,
> > changing the skeleton file at one of the places, and if there is  
> > something
> > already written, all will look normal. So perhaps, in the case of the
> > precedence rule, one should give a warning if both methods are used.
>
> It's clear to me that %foo overriding --foo is misleading to the user
> invoking Bison from the command line.
>
> I think you're now saying the reverse could also be misleading.  I  
> agree.
> Imagine the user who edits the grammar file and then types make.   
> He may
> not realize that the makefile invokes Bison with --foo overriding  
> the %foo
> he just wrote.

I am thinking about the psychology. In the case of writing a library  
override, the editing location of the user is always clear. In this  
case, both might be used. And any one overriding the other might be  
confusing.

So this suggest sticking to Paul's suggestion for now: if both are  
used, one gets an error.

> Maybe we're trying to be too helpful, but I'm not sure.
>
> Here's another proposal.  Bison would complain about any conflict  
> between
> --foo and %foo.  However, it would let --force-foo override %foo.
>
> I believe there are only a handful of options for which this should
> actually be done:
>
>   --defines
>   --output
>   --name-prefix
>   --file-prefix
>   --skeleton
>
> By the way, should there even be a --language?  Isn't the target  
> language
> always so tightly coupled with the grammar file that %language should
> always be used instead?  Why would anyone ever want to override it?
> Paolo, what do you think?

Another idea that came to my mind, which I just mention, is to  
separate Bison language and compiler options. Language options should  
then go in the .y file, and the compiler options in some other file.  
But perhaps this is not the practise of other compilers.

But by this idea, language options should then not be alterable by  
startup arguments. In particular, %language should only not be  
duplicated by a --language. Perhaps this idea is what you sense  
intuitively.

  Hans Aberg