Re: \version statement, etc.

[David Wright]

On Tue 17 Oct 2017 at 11:31:46 (-0700), Paul Scott wrote:
> On Tue, Oct 17, 2017 at 08:14:06PM +0200, David Kastrup wrote:
> > Paul Scott <address@hidden> writes:
> > 
> > > On Tue, Oct 17, 2017 at 08:03:44PM +0200, David Kastrup wrote:
> > >> 
> > >> That is the whole _point_ of a warning: LilyPond is able to complete
> > >> the job which _may_ mean that it works perfectly but it cannot be
> > >> sure.  For example, because it does not know for which version some
> > >> file has been written.
> > >
> > > I am trying to use version statements correctly and efficiently.
> > > Why doesn't my example work or how should I do it differenly?

Perhaps you might think of the version statement like the strand line
on a beach which shows how high the water has ever been.

When you wrote LP files for 2.18.2, using its notation, you probably
put \version 2.18.2 in the files. Those files will, in the absence of
incompatible changes to LP's behaviour, still work with 2.19.49, say.

If LP were to make such changes, or you were to re-edit those files
for some reason, you would start by running convert-ly which would
update them and change the version to suit. That's like the sea
pushing the strand line further up the beach.

But files you write now will contain \version 2.19.49 (I'm lagging),
and might have modern constructions in them that LP 2.18.2 wouldn't
understand. Whether or not those construction throw an error, the
version warning will alert you to the fact that LP might misinterpret
what it read from the file.

> > LilyPond expects a \version statement in the main file.  Put one there.
> > convert-ly can do this for you (probably leave off the -d option).
> 
> In all my projects the .ily file with the \version statement is the main
> file with the music in it.  There is .ly file for each instrument/part
> which includes the .ily file.  I haven't had to put a \version statement
> in each .ly file until 2.19.80.

But it's pointless *not* to include a version statement. You aren't
expected to keep editing it so that it remains "up to date".

The only time I miss them out is when writing an MWE for posting
here. I would like people running 2.18.2 (and older) to be able
to run them without the hassle of editing them, but I can't be sure
about how low a version number would still be valid. For an MWE
it hardly matters because the code can easily be examined in its
entirety without much effort.

Cheers,
David.