[gentoo-dev] Slotting Tcl/Tk

[gentoo-dev] Slotting Tcl/Tk

[Eamon Caddigan]

Howdy, y'all.

I rekkon it's time we reopen bug #4450. I thought I'd post it to
gentoo-dev because a) tcl/tk is important, and can break a lot of stuff
and b) I'm relatively inexperienced with writing ebuilds, and would
appreciate comments and suggestions. 

Adios,
Eamon Caddigan


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Re: [gentoo-dev] Slotting Tcl/Tk

[Stanislav Brabec]

On Fri, Nov 21, 2003 at 02:42:10AM +0000, Eamon Caddigan wrote:
> Howdy, y'all.
> 
> I rekkon it's time we reopen bug #4450. I thought I'd post it to
> gentoo-dev because a) tcl/tk is important, and can break a lot of stuff
> and b) I'm relatively inexperienced with writing ebuilds, and would
> appreciate comments and suggestions. 
> 

SLOTting packages, which provides identical interface and cannot seamlessly
co-exist in system, is bad idea.

You can have installed two packages using two SLOTs in one time. But if you
update or install anything, current packages/ebuilds have no intelligence to
guess, for which SLOT they should be compiled. It will compile for this SLOT,
which has created actual instances of /gentoo/usr/lib/*Config.sh!

Two tcl/tk versions are partially acceptable for binary-only distributions
where different soname is reasonable protection. But for systems compiled from
source, risks of version mismatch is very high.

Tcl/tk extensions built randomly for tcl/tk 8.3 and 8.4 will not work well when
they are combined.

Summary:

Tcl/tk slots is bad idea. It can change only if somebody will hack all
dev-lang/tcl (and some extra) ebuilds to be able to create simultaneously
packages for both tcl/tk 8.3 and 8.4 (if they support building for both
versions).

---

Tcl/tk situation is NOT similar to Apache 1/2 or GNOME 1/2, which has 
different interfaces and different library names.

This situation is very similar to libc5 and glibc few years ago - yes, you can 
install both in one system. Yes, existing packages will continue to work. But 
oops - new packages using one library compiled for libc5 and one for glibc
will most probably crash.

There is a chance for simple SLOTting - using /opt/prefix for alternative tcl 
versions. In such case you have to install all extensions twice - once for main
system, once for alternative. For more, see insight ebuild.

-- Stanislav Brabec

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[gentoo-dev] and Python! (Re: [gentoo-dev] Slotting Tcl/Tk)

[Jean Jordaan]

Hi all

> You can have installed two packages using two SLOTs in one time. But if you
> update or install anything, current packages/ebuilds have no intelligence to
> guess, for which SLOT they should be compiled. 

I'm really not up to speed on this issue, but it feels very similar to
Python hassles I've had. We run Zope, which uses Python 2.1.3, but we
also use packages that require other Pythons, including 2.3. The Zope
Product ebuilds are clever enough to install into the site-packages of
multiple /usr/lib/python2.*, but other Python module ebuilds want to
install into only one (the newest?) Python's site-packages. It would be
necessary to say "I want to emerge this module for the Python in that
SLOT", and to have this reflected in the output of the gentoolkit tools.

-- 
Jean Jordaan
http://www.upfrontsystems.co.za


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Re: [gentoo-dev] Slotting Tcl/Tk

[Thomas de Grenier de Latour]

On Fri, 21 Nov 2003 14:44:41 +0100
Stanislav Brabec <utx@gentoo.org> wrote:

> You can have installed two packages using two SLOTs in one time. 

Hmmm... not the same version of two packages afaik, at least not
cleanly: the second installation would overwrite the db entry of the
first one, making portage forget half of the files, no?

-- 
TGL.

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Re: [gentoo-dev] Slotting Tcl/Tk

[Stanislav Brabec]

Thomas de Grenier de Latour wrote:
> On Fri, 21 Nov 2003 14:44:41 +0100
> Stanislav Brabec <utx@gentoo.org> wrote:
> 
> > You can have installed two packages using two SLOTs in one time. 
> 
> Hmmm... not the same version of two packages afaik, at least not
> cleanly: the second installation would overwrite the db entry of the
> first one, making portage forget half of the files, no?

Portage does not forget anything (even in case all files are in the same
SLOT). Only filesystem "forgets" old file overwritten by new one.

So there is a basic condition for non-conflicting packages and seamless
SLOTs: There must not be no files owned by both files or SLOTs. (This
should be stated somewhere in ebuild howto.)

You can have apache1 and apache2, gtk1 and gtk2 installed at once,
because mainstream developers of those packages has changed file names.

-- 
Stanislav Brabec
http://www.penguin.cz/~utx, ICQ 116020046

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[gentoo-dev] Re: Slotting Tcl/Tk

[Eamon Caddigan]

Stanislav Brabec <utx@gentoo.org> wrote:
> Thomas de Grenier de Latour wrote:
>> On Fri, 21 Nov 2003 14:44:41 +0100
>> Stanislav Brabec <utx@gentoo.org> wrote:
>> 
>> > You can have installed two packages using two SLOTs in one time. 
>> 
>> Hmmm... not the same version of two packages afaik, at least not
>> cleanly: the second installation would overwrite the db entry of the
>> first one, making portage forget half of the files, no?
>
> Portage does not forget anything (even in case all files are in the same
> SLOT). Only filesystem "forgets" old file overwritten by new one.
>
> So there is a basic condition for non-conflicting packages and seamless
> SLOTs: There must not be no files owned by both files or SLOTs. (This
> should be stated somewhere in ebuild howto.)

This would be easy enough to implement for Tcl/Tk. However, as the
consensus seems to be that SLOT-ing Tcl/Tk is a bad idea, I won't
bother. 

-Eamon


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[gentoo-dev] Re: Slotting Tcl/Tk

[Eamon Caddigan]

Stanislav Brabec <utx@gentoo.org> wrote:
> 
> Tcl/tk slots is bad idea. It can change only if somebody will hack all
> dev-lang/tcl (and some extra) ebuilds to be able to create simultaneously
> packages for both tcl/tk 8.3 and 8.4 (if they support building for both
> versions).

If this is true, then I feel it's imperative that Tcl/Tk 8.4 become
stable, and all other packages in portage are made to work with it. 8.4
is about a year old now, and I find it unacceptable that it's only
available as an "unstable" package. This situation reminds me of that
*other* distro.

I agree that there are a lot of potential issues involved with SLOTting
this package. Unfortunately, the only alternatives -- a similarly
massive effort to make sure everything works with the newest version, or
sticking with an increasingly out-of-date package -- seem worse.

Thoughts?

-Eamon


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Re: [gentoo-dev] Re: Slotting Tcl/Tk

[Mike Frysinger]

On Friday 21 November 2003 09:40, Eamon Caddigan wrote:
> I agree that there are a lot of potential issues involved with SLOTting
> this package. Unfortunately, the only alternatives -- a similarly
> massive effort to make sure everything works with the newest version, or
> sticking with an increasingly out-of-date package -- seem worse.

well, do any bugs exist in bugzilla about 8.4.4 ?
you could always bootstrap a stable system (after marking 8.4.4 stable 
locally) and see if everything works out.  ive been using 8.4.4 on my systems 
w/out problems ...

i'd agree with utx here on why trying to SLOT a package just because you want 
to compensate for a newer one being broken is the wrong path to take.

it's like when people suggested SLOTing openssl just because you have to 
recompile packages against the newer openssl ... it's a hack, not a solution.
-mike



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