Re: Identify included files

[Matt Wallis]

On 06/06/2020 16:34, Fr. Samuel Springuel wrote:
> I have now updated the repository I posted earlier 
> (https://github.com/rpspringuel/lilypond_make) to contain two additional 
> branches:
>
> GNUmake_dependencies: Implements dependency generation as described in the 
> GNUmake manual
>
> mad-scientist_dependencies: Implements dependency generation as described in 
> the article that Matt linked.  Right now I’ve used a simple sed script in the 
> recipe to add the midi file to the targets of the dly file generated by 
> LilyPond, but I haven’t given up on a more general solution.
>
> Comments from anyone willing to look these over and play around with them are 
> greatly appreciated.

Hi Samuel,
Great work! I have not had a play, but I have had a quick look through
https://github.com/rpspringuel/lilypond_make/blob/mad-scientist_dependencies/Makefile

Just a few comments, mostly general things about makefiles, practices 
that I usually follow.

Be clear about the difference between = and :=. You are using = when := 
would work fine.

Put everything that moves (!) into a variable. For example, I'd have

PDF_DIR := PDF/

Include the backslash when you define a directory (as above). This is a 
habit I've got into and now rely on. It helps me.

Use `mkdir -p` to create dirs because it doesn't fail if the directory 
exists. Having said that, this goes against another principle I often 
try to follow: Write software according to Dijkstra's weakest 
preconditions, by making it as fragile as possible (but no more 
fragile!). That way the program will break if the implementation does 
not follow the design, making it easier for bugs to become apparent. 
With the `mkdir -p` example, it could be argued that because these 
directory targets only come into play via order-only prerequisites, they 
should never be called upon unless the directory does not exist...

I found 
https://lists.gnu.org/archive/html/lilypond-user/2020-05/msg00148.html 
very interesting.
It describes how to get lilypond to print out dependencies. Have you 
looked into this?

Best regards,
Matt