Re: T3154 work - round 2 - question.

[David Kastrup]

Ian Hulin <address@hidden> writes:

> However, the it looks like the \midi blocks still need to be stackable

Do they?  It seems so far we got away without that?

> and I've just figured out the way you implemented the things for \paper¸
> and I think we could use a set of general procedures/method to handle
> output_def stacks, modelled on what you did for \paper.

Uh, I don't think I did anything much for \paper.  I have not, as far as
I can see, touched any of the internal ways of organizing data.  At best
I provided hooks into them.  Or changed in the parser when what gets
copied from where in order to deal with problem reports.

> I.e.
> (<blah> could be one of papers, midis, or layouts)
> get_<blah> // used by parser to set up an initial output_def (though
> get_midi has a potential name clash with a method in Midi_walker::)
> These probably need to stay as separate functions for each output_def type.
>
> init_<blah> // initialize the stack using a parser variable
> push_<blah> // push an output def onto the stack using the
>           // parser variable
> pop_<blah>  // push an output def from the stack using the
>           // parser variable
> set_<blah>  // set the value of the topmost stack item.

We don't really have stacks for paper.  There is something like a parent
setting somewhere and \paper is the parent for \layout or the other way
round, but that really only concerns lookup.

> void
> init_od_stack ( string od_type, Lily_parser *parser)
> {
>   switch (od_type.c_str())
>     {
>     case 'paper':
>       {
>         //init_papers (parser);
>         SCM stack_parser_var =
>               parser->lexer_->lookup_identifier ("$papers");
>         SCM default_parser_var =
>               parser->lexer_->lookup_identifier ("$defaultpaper");
>         SCM od_property_val = ly_symbol2scm ("is-paper");
>       }
>       break;
>     case 'midi':
>       {
>         //init_midis (parser);
>         SCM stack_parser_var =
>               parser->lexer_->lookup_identifier ("$midis");
>         SCM default_parser_var =
>               parser->lexer_->lookup_identifier ("$defaultmidi");
>         SCM od_property_val = ly_symbol2scm ("is-midi");
>       }
>       break;
>     case 'layout':
>       {
>         //init_layouts (parser);
>         SCM stack_parser_var =
>               parser->lexer_->lookup_identifier ("$layouts");
>         SCM default_parser_var =
>               parser->lexer_->lookup_identifier ("$defaultlayout");
>         SCM od_property_val = ly_symbol2scm ("is-layout");
>       }
>       break;
>     }
>   Output_def *my_output_def =
>       ((stack_parser_var == SCM_UNDEFINED)
>               || scm_is_null (stack_parser_var))
>                   ? 0 : unsmob_output_def (scm_car (stack_parser_var));
>   my_output_def =
>       my_output_def ? my_output_def
>               : unsmob_output_def(default_parser_var);
>
>   my_output_def =
>       my_output_def ?
>       dynamic_cast<Output_def *> (my_output_def->clone ())
>               : new Output_def;
>   my_output_def->set_variable (od_property_val, SCM_BOOL_T);
>   return my_output_def;
> }
>
> WDYT?

That looks like you want to institute a completely new stack structure
running in parallel with the \layout/\paper duplicity.

Make no mistake: the current setup is an incoherent mess.  But putting
stacks on top of the incoherent mess is not going to fix that.

So the main question is: what are you trying to do?  What is the
ultimate goal?

-- 
David Kastrup