DEP14 policy for two dots

[Raphael Hertzog]

On Fri, 04 Nov 2016, Ian Jackson wrote:
> Raphael Hertzog writes ("Re: DEP14 policy for two dots"):
> > We have defined simple "readable" mappings for the common cases that
> > we encounter frequently. Now if we need mappings for silly things
> > that we don't encounter, I would suggest to use something easily
> > reversible and extendable.
> 
> My proposal is reversible.  It does not need to be extensible.

So what about "..."? Would it give ".#.#."?

What's the rule to apply? if it's just to drop the "#", then yes
it's reversible in a single step. If it's "s/\.#\./../g" then you need
to do it multiple times until you no longer find ".#.".

I wanted something extensible because what's allowed in git ref names
might evolve. It would not be the first time that a special syntax
is introduced with a new feature.

> > My suggestion would be to allow "#<hexadecimal unicode code point>#". 
> > Thus my personal preference would be to replace ".." with ".#2e#".
> 
> This is a bad idea because it (implicitly) makes the conversion
> nondeterministic.

We define the conversion rule in DEP-14. We can define it in a
deterministic way.

> You might write some rule about which . should be replaced by #2e#
> but it would be easy to misimplement.

It's possible to misimplement almost any rule.

> Also if we are going to introduce an arbitrary codepoint quoting
> system like this it should be identical to quoted-printable (bad as
> that is).

It's limited to ASCII but I guess it's highly unlikely that we will
one day allow unicode in version strings. So yes, that would be an option
as well. Given that "=" is forbidden in version numbers and allowed in git
refnames, it should work.

Which of # or = is more likely to be used for a new syntax/feature in git?
My bet would go for "#" so that "=" is an even better choice.

Cheers,
-- 
Raphaël Hertzog ◈ Debian Developer

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