Re: How to get warnings for unused parts of a file?

[Omid Mo'menzadeh]

I'm just re-stating this to make sure I'm getting it right: Definitions are lazy, and the _expression_ in front of # is lazy too, so it gets a chance to see the definition once it's done? Am I right?

That's good to know!

On Sat, Oct 2, 2021 at 4:00 PM David Kastrup <dak@gnu.org> wrote:

"Omid Mo'menzadeh" <omid.mnzadeh@gmail.com> writes:

> Of course!I just attached two files that demonstrate the difference.
>
> On Sat, Oct 2, 2021 at 3:30 PM David Kastrup <dak@gnu.org> wrote:
>
>> "Omid Mo'menzadeh" <omid.mnzadeh@gmail.com> writes:
>>
>> > I didn't know about $ at all! Where in the documentation can I find more
>> > about it? It was hard to search for!
>> >
>> > I tried it, but it doesn't seem to find my variable "vocal" defined in
>> the
>> > same .ily file. I tried using #(top-repl) and $(top-repl) too, in the #
>> > version it knows what \vocal is, but in the $ version it doesn't.
>>
>> How about a minimal example exhibiting the problem?
>>
>> --
>> David Kastrup
>>
>
> \version "2.22.1"
>
> vocal = \relative c'' {
>   a4 b c d |
> }
>
> $(if (not (defined? 'is-loaded-file)) #{ \score { \vocal } #})

Well, that one's a timing problem.  You couldn't write

vocal = \relative c'' {
  a4 b c d |
}

\vocal

either.  The reason is that the assignment is not complete before
LilyPond has a chance to check whether something like \addlyrics { Ah }
follows, and so when it looks at the next thing that comes up to make
that decision, \vocal is not yet defined.  So there really needs to be
anything after that assignment that does not immediately reference
\vocal .

With #, LilyPond does not allow different syntactic functionality, so
when it sees # it does not bother evaluating it until after it has
completed the assignment, being sure that it won't have to add something
like \addlyrics ... to the _expression_ to be assigned.

This is one case where minimal examples tend to fail more often than
actual use of assigned variables in practice, because usually when you
employ variables seriously, you don't reference them immediately right
afterwards.

--
David Kastrup