Re: trying out the c++ parser skeleton / b4_post_prologue

[Anthony Heading]

Akim Demaille wrote:

> But I can't see elegant means to achieve this.
> [...]
> What do you propose?

Well, as you mention below, I was thinking of an approach where
the semantic action code is created as a member function of
a user class.  But I would concur it comes with problems of
its own and might be inelegant, even if the end result would
be good.

> exposing implementation details.  yytname is a nice example of what,
> imho, should not have been documented.  Rather, the function that is
> in the documentation
> [...]
> for (i = 0; i < YYNTOKENS; i++)
>   @{
>     if (yytname[i] != 0
>         && yytname[i][0] == '"'
>         && ! strncmp (yytname[i] + 1, token_buffer,
>                       strlen (token_buffer))
>         && yytname[i][strlen (token_buffer) + 1] == '"'
>         && yytname[i][strlen (token_buffer) + 2] == 0)
>       break;
>   @}
>
> should be provided.  The user shouldn't have to copy it, it should be
> provided.

I don't agree here.  A raw array is a good interface. For example,
I want read it once and build my own hash table of tokens.  That's
hard if the data is hidden behind some arbitrary linear-scan search
interface.

> I'm not eager to bind myself to implementation details.  If something
> smarter than an array could be used, I'd be sad to be bound to it
> because of a public or protected.
>
> My strategy is more to look for the use cases, and them design the
> interface that suits them.

Well, there's balance in all things.  In the case of the token
names and numbers, they are so fundamental that I wonder if it's
misguided to believe you can anticipate all the reasonable
use-cases with the functional interface approach you suggest
above.

To break the link with implementation internals, you could just
choose to document and make public a different array to that
which might be used internally.  I obviously don't disagree about
exposing internals, but any data tables become much less flexible
tools if the bison designers force a particular access algorithm.

Rgds

Anthony