Re: In preparation of Lua-5.3 - versioned binaries of Lua?

["Kamil Rytarowski" <n54%gmx.com@localhost>]

----- Original Message -----
From: Greg Troxel
Sent: 04/21/14 11:55 PM
To: Kamil Rytarowski
Subject: Re: In preparation of Lua-5.3 - versioned binaries of Lua?
 "Kamil Rytarowski" <n54%gmx.com@localhost> writes:

> Currently we maintain two versions of Lua in pkgsrc: 5.1 and
> 5.2. However they are conflicting, because they install binaries as
> bin/lua. It prevents me for easily using unmodified software designed
> for Lua 5.1 (like Luapress) in a system where the main version is Lua
> 5.2. The Lua generations 5.1 and 5.2 aren't fully compatible.
>
> Python packages ships with versioned binaries: python2.6, python2.7, 
> python3.3.
>
> Could we follow the same pattern for Lua? We may be soon ready for
> inclusion of Lua 5.3 without damaging the current Lua ecosystem, as
> the backward compatibility between 5.3 and earlier generations is
> still unknown.

We could, but this is a somewhat difficult decision. For perl, we have
only one version, and in theory the newer version can run the old cold.
In practice, that's either true or close enough. python, especially
with 3.3, is clearly not adequately compatible. Being able to have
multiple versions drags in quite a lot of work. So the question is how
much pain only having one lua version installed at once causes, and if
that pain is more than or less than the pain of implementing multiple
simultaneous version support. And, it's about who is pained, and if
they fix it :-)

Are you saying that luapress really doesn't work with lua52? That is a
good argument that lua should be versioned like python. That will lead
to any lua library that could be used by something else having to be
lua-foo, and hence lua51-foo vs lua52-foo. So this is a fair bit of
churn, but maybe needed churn. 


---------

Hello,

Thank you for your feedback. Lua generations (5.1, 5.2) in the field of 
backward-compatibility are much closer to Py2 and Py3, than the Perl backward 
compatibility of regular upgrades (most of CPAN is reusable without 
modifications).

Actually, adjusting Luapress [1] for 5.2 isn't that difficult, since it's just 
500 LOC static-content-generator. The Lua team is in a more comfortable 
situation than Perl or Python developers, because there is a smaller code-base 
around and the cost of non-backward-compatible modification of the language is 
much lower.

I'm also heading Sputnik [2], that pulls dependencies that (from my knowledge) 
aren't Lua-5.2-compatible (but it may be verified).

In case of versioning Lua and Lua packages we can make room for upcoming 5.3.

[1] https://github.com/Fizzadar/Luapress
[2] http://sputnik.freewisdom.org/