Re: Is there an equivalent of #define ... #ifndef ... #endif in lilypond?

[Michael Hendry]

Helge Kruse-2 wrote:
> 
> Am 18.02.2012 00:30, schrieb Michael Hendry:
>>
>> Obviously, I can comment out the sections I don't want during data entry
>> work, and remove the comments once the work is complete, but it would be
>> handy to be able to use a C-like construct like this:
>>
>>
>> #DEFINE NotYet
>> ...
>> #IFNDEF NotYet
>> \book {
>>      \bookOutputName "Chez Fernand (alto)"
>>      \new Score
>> <<
>>      \transpose f' d {\TheChords}
>>      \new Staff
>>      \repeat unfold 13 {
>>              s1 \noBreak s1 \noBreak s1 \noBreak s1 \break }
>>      \transpose f' d {\TheHead}
>>>>
>>      \header {piece = "Alto Sax"}
>> }
>> #ENDIF
> What about block comment? I can't see why editing the file to change 
> #DEFINE is preferred to editing the file to change the block comment.
> 
> %{
> \book {
>       \bookOutputName "Chez Fernand (alto)"
>       \new Score
> <<
>       \transpose f' d {\TheChords}
>       \new Staff
>       \repeat unfold 13 {
>               s1 \noBreak s1 \noBreak s1 \noBreak s1 \break }
>       \transpose f' d {\TheHead}
>  >>
>       \header {piece = "Alto Sax"}
>   }
> %}
> 
> Helge
> 
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> 
> 


Thanks for your comment, Helge. Of course, I know about block comments, and
if there were only one section I wanted to suppress during the development
of piece that would be fine. But I have several sections I'd like to switch
off during data entry, and I'd like to be able to switch them all on again
with a single edit without having to remember where they are - in much the
same way as a C programmer will scatter debugging code through a project,
and switch it off for the final compilation.

So it would be:

#define debugging

... several pages of code ...

#ifdef debugging
... print something on the screen, and await a user response ...
#endif

... several more pages of code ...

#ifdef debugging
... do something else that's useful in the debugging process ...
#endif

... and so on ...

Of course, for lilypond I'd be using the process in reverse - leaving out
known-to-function bits of code while concentrating on other bits - and it's
good practice not to keep commenting out and commenting in - there's always
the risk of accidentally removing a crucial character, or getting the
bracketing wrong.

I know I'll be accused of laziness, but I'd like to be able to concentrate
on the music, and be able to develop reliable blocks of supporting code I
can incorporate in any piece - in this instance I'd have to use a variable
in place of "Chez Fernand" to make the code more portable, it could then be
brought in using "\include" wherever I wanted it.

I envisage a series of #define statements at the head of the main .ly file
such as:

#define concert_part
#define guitar_part
#undef alto_part
#define clarinet_part

which would alter the output from the included "parts.ly" file.

I'd previously had a look at tags in Lilypond, but couldn't see how to apply
them cleanly in this context.

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