Syntax clarification/change/improvement for -d[value]

[James]

I guess this is part of what GLISS is, currently issue 2139 wants to
clarify some usage options


ELuze pointed out that:
-------

when reading the line

 -d,--define-default=var=val

it is not intuitively clear where to use equal signs - does the 1st
equal sign need to be written when writing -d or not? it's only after
looking at the examples that it becomes clearer.

suggestion:

-dvar=val, --define-default=var=val

and consequently for all the other command line options:

-eexpression, --evaluate=expression
-fformat, --format=format
--------

He then went on to say...


-dgui works as well as -d=gui=#t but -d=gui does not!

and
-d=include-settings="C:/data/ly/includes/myInit2.ly" doesn't work!

so it seems that you need the equal sign when going for the
--define-default variant and -d=var=val works if you have the whole
assignment after the equal sign but not with the implicit assignment
of the truth value?!

I would be happy with a definition like you describe (after clarifying
the 1st equal sign) , e.g.

[-d | --define-default] [=]var[=val] (if that's not too confusing)

maybe adding

[ly:set-option 'var 'val)

and *not* listing all the options as you propose. it would be enough
to list the options which are not consistent.

there is another category of command line options which obviously can
not be invoked as an internal function (e.g. -dgui): they should be
listed as exceptions to the general rule we are trying to establish:

  #(ly:set-option 'log-file "loglog" )
  #(ly:set-option 'include-settings "G:/data/ly/includes/myInit2.ly")
  #(ly:set-option 'gui #t)
  #(ly:set-option 'verbose #t )

------

My problem is knowing how to articulate this in the correct way/terminology.

>From this little information is there a term to use for those that
cannot be used with -d=var=val, and what the correct way to explain
why -d=include-settings="C:/data/ly/includes/myInit2.ly" doesn't work
- I get it technically, the command cannot take a value from a 'third
party' so to speak and apply it, it needs it first hand.

Failing all that, what about removing the '=' altogether make it an
invalid syntax and just stick wth -dxxx

James