Re: Purity of yyerror etc.

[Paul Eggert]

Sorry, that patch went wayyy over my head.

Often, when I am thinking of making a patch like that, I find it
useful to write the patch for the documentation.  It's quite helpful
to have a clear description of how things will change for the users,
and the documentation exercise often suggests ways to improve or
simplify the behavior.

Anyway, there seem to be several issues here:

1.  yyval/yyloc/b4_pure_args versus yylval/yylloc/b4_lpure_args

    What is this issue?  Can it be stated briefly?  Why have two forms?

2.  %parse-param versus %pure (and perhaps %location?)

    Why are there two somewhat-different options here?  Is it some
    backward-compatibility issue?  If so, what is the preferred option
    these days, and how does it differ from the old-fashioned way?
    And what does %pure have to do with %location?

3.  yacc.c versus glr.c

    yacc.c needs to support older features for historical reasons,
    but glr.c doesn't.  Which features are these?


> It results in a program that can have many arguments in function calls.

Why not instead pass a single argument that specifies the parsing context?