Re: ancient convert rules

[Jean Abou Samra]

Greetings everybody,

Le 30/08/2020 à 21:06, David Kastrup a écrit :
> Jonas Hahnfeld <hahnjo@hahnjo.de> writes:
>
> > For https://gitlab.com/lilypond/lilypond/-/issues/6024, I've been
> > looking at python/convertrules.py and wonder if we really need all
> > ancient rules starting from version 0.1.9. Right now, a majority of
> > these won't even apply because Python 3 is much pickier about bad
> > escape codes in the regular expressions. Example:
> >      re.sub('\\musicalpitch', '\\pitch', s)
> > is wrong because \\ only escapes for the string and neither \m nor \p
> > are correct escapes in a regular expression. For this case, it's easy
> > to fix with raw strings and I think I was able to resolve most errors
> > so that all rules are able to run, but I've no way to guarantee that my
> > edits are correct.
> >
> > To make the story short: Can we maybe instead drop any rules older than
> > 2.12.0? Its last minor release 2.12.3 is more than 10 years ago.
> Music tends to stick around really really long once entered.  Admittedly
> old convert-ly rules tended to be a lot less thorough than what we tend
> to do now.
>
> Doing
>
> dak@lola:/usr/local/tmp/The-Mutopia-Project$ git grep -h '\\version'|sort 
> -u|less
>
> gives me something starting with
>
> \version "1.9.8"

For the record, I finally figured out why we had different results: I 
had been
searching only the ftp/ directory. Naturally, what you did is more accurate.

> What if we kept a legacy convert.ly that went from the origin to, say
> 2.12.0 that was still Python 2 based?  And then had the new, Python 3-based
> convert.ly start from 2.12.0?
>
> This would provide a way for anybody who needed to get old source code up
> to the current standard to do so, and would eliminate the burden of
> converting the whole file to Python 3.
>
> Thanks,
>
> Carl

Maybe the solution is just to mention somewhere in the documentation of
convert-ly that if the user wants to upgrade from older that 2.12 or 
whatever,
they can use the convert-ly from LilyPond 2.18?


> I definitely overlooked how often there are*too many*  backslashes in
> the code. So there are a lot more changes requried than what is in merge
> request 363:

Also, you fixed invalid escape sequences -- thanks for that! --, but 
pylint can't
spot cases where there aren't many actual backslash characters in the 
resulting string
to escape backslashes in the regular expression (the second level of 
escaping), like in Jonas'
original example. This is why it seems all ancient rules would require a 
decent
amount of work to be made to work with Python 3, if I understand correctly.

Cheers,
Jean