\relative proposal: putting absolute pitches anywhere within \relative block using @-sign

[nothingwavering]

This is a breakaway thread from the one with the subject "Proposed new 
available and recommended behavior of \relative"

I am *OPPOSED* to the proposal to change \relative syntax, as the proposal now 
stands.  I think it is confusing to new users to have the first pitch in a 
\relative block be absolute and the rest be relative.

But I have another idea.  I'm not sure if people will like it right away 
because it means changing/adding MORE syntax, but I think it will be MORE 
useful and more *intuitive*!



Here's the idea.

1. Define absolute octave syntax with the @-sign (let it be a mnemonic for 
_A_bsolute) to be the syntax for temporarily specifying an ABSOLUTE PITCH 
within a \relative block, such that the next pitch, if it doesn't use the 
@-sign also, is relative to the absolute pitch.

2. Keep \relative X { ... } working the same way as it is (DON'T make 
convert-ly change it around).

3. Make \relative { X ... } work such the first pitch after the brace is 
expected to be an absolute pitch syntax with the single equal sign.  If it is 
not, a warning is printed and the pitch is interpreted as relative to c' (the 
current behavior, except for the warning, right?).

Why a new syntax?  I frequently find that if I jump to the end of a big, long 
\relative { ... }, then frequently I don't remember which octave I'm in.  
Octave check is not a solution, because if I guess the part that comes before 
the = sign wrong, I'll keep getting warnings until I fix it.  What is wanted is 
a way to temporarily jump into absolute note entry mode.  An @-sign comes 
immediately after the note name, and is followed by any apostrophes or commas 
as necessary to specify the absolute octave.

Examples:

1.      { c4 c' c@'' c@, }

        These are interpreted as absolute pitches, so the @-signs are redundant 
here.  
        They could be silently ignored, or the at signs could be an error 
outside of \relative blocks.

2.      \relative c' { c4 g, g@' g }
        
        This is the same as { c'4 g, g' g' } in absolute mode, if I read it 
right.  
        The last g is relative to the absolute g.

3.      \relative { c@'4 c g' c }

        This is the same as { c'4 c' g' c'' } in absolute mode.  
        This would be the form that new users of LilyPond would be encouraged 
to use in the documentation.

4.      \relative { c4 c g' c }
        
        This is the same as 
                \relative c' { c4 c g' c }
        
        EXCEPT that a warning will be printed about encountering 
                \relative { X ... } 
        where X is not specified absolutely (with at-sign).


What do people think?

--Christopher