Re: lay out

[Mats Bengtsson]

Aaron Mehl wrote:
> Ok here is where I am confused. There is a structure
> for files which makes a file valid.
> Then there is a grammar which must also be followed
> for the lanuguage of lilypond.
>  
> I get the feeling after reading the docs that the
> structure of lilypond is loose.
>
> What I mean is that it appear (if I am not wrong) that
> there are elements that can appear a number of places
> in a document and others that can appear only in
> certain places.
>
> I want to be able to generalize and also limit the
> structure of a basic lilypond file:
>
> lets say a file with a melody only.
>
> If I ask the question what elements must a lilypond
> file have or it won't be valid structuraly will I get
> an answer?
>
> If I ask for a valid parent child relationship of
> elements will I find such a thing?
>
> This issue is compounded for me by most lilypond
> examples which use includes or variables x = y
> so that it is often hard to see what the structure is.

For me it's the opposite. I find it much harder to see
the structure if you only have a long \score{...} where
I have to scroll several pages from beginning to end.

One thing that may confuse you is that some of the structural
elements are optional. For example,
\book{
  \score{
    {c d e f}
  }
}
can be abbreviated into
{c d e f}

Probably, you wouldn't have that much problems with the basic structure
if you had a background in programming languages like Pascal or C or
Scheme than with the very strictly specified grammar of XML.
To cite Han-Wen, the strict formal definition of the input grammar
can be found in the source code file parser.yy. However, I
agree completely with you that we should have a basic description
not only of the syntax but also of the semantics of the
basic building blocks. Even though I've been using LilyPond
since version 0.0.xx, I'm still confused by some aspects,
especially when it comes to \book{...} and what happens if you
have several \layout{...} blocks at the top level.

The basic ideas, though, are not that hard. At the top level
of the file, you can have "macro definitions" xxxx = ...,
you can have \header{...} blocks, \paper{...} blocks,
\layout{...} blocks and, of course, \score{...} blocks (I've
probably forgot some others as well).
The \header and \layout can also be moved inside the \score{...}
if you wish and in that case the only apply to the current score,
otherwise they apply to all scores.

   /Mats

> I am not complaining rather I am trying to understand.
>
> I realize part of my problem comes from my experience
> with xml/html where there are strict rules for nesting
> and validity and wellformedbness...
>
>
> A documentation page titled file structure should lay
> down some rules for file structure instead of listing
> a few of the top level elements.
>
> I for my part find it confusing when an element is not
> nested. Although I realize that with lilypond there is
> less worry about missing brackets that way.
>
> I will read some more and experiment some more and see
> what I come up with.
>
> Aaron
> --- Mats Bengtsson <address@hidden> wrote:
>
>
> > (Graham, or someone else, we should really try to
> > make sure that
> > all commands and reserved words available in
> > LilyPond are listed
> > in the Index. \layout is one of those missing. Doing
> > such an exercise
> > would also help identifying what information is
> > missing from the manual
> > today.)
> >
> > Part of an answer to your question can be found in
> > the
> > sections "Changing context default settings" and
> > "Defining new contexts" in the manual. There's also
> > some
> > information in "Line length", but there doesn't seem
> > to be
> > any introduction to the concept anywhere. For
> > example, I couldn't
> > find any information on that you can put a
> > \layout{...} block
> > on the top level of the file to make it apply to all
> > scores in the
> > file (or at least within the \book) whereas it will
> > only apply to
> > the current score if you put the declaration inside
> > \score{...}.
> >
> >    /Mats
> >
> >
> > Aaron Mehl wrote:
> >
> > > Hi   all,
> > >
> > > In a previous email I asked if layout replaced
> >
> > paper.
> >
> > > I was told to look at outputs, which I did. The
> >
> > paper
> >
> > > output section details \paper{}
> > >
> > > but I see no mention of \layout {}
> > >
> > > where in the docs is \layout discussed?
> > >
> > > Thanks
> > > Aaron
> > >
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> >
> > --
> > =============================================
> >         Mats Bengtsson
> >         Signal Processing
> >         Signals, Sensors and Systems
> >         Royal Institute of Technology
> >         SE-100 44  STOCKHOLM
> >         Sweden
> >         Phone: (+46) 8 790 8463                         
> >         Fax:   (+46) 8 790 7260
> >         Email: address@hidden
> >         WWW: http://www.s3.kth.se/~mabe
> > =============================================
>
>
>
>
>                 
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--
=============================================
        Mats Bengtsson
        Signal Processing
        Signals, Sensors and Systems
        Royal Institute of Technology
        SE-100 44  STOCKHOLM
        Sweden
        Phone: (+46) 8 790 8463                         
        Fax:   (+46) 8 790 7260
        Email: address@hidden
        WWW: http://www.s3.kth.se/~mabe
=============================================