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Re: Dependency loops considered harmful?



Michael Schwendt wrote:
On Wed, 3 Sep 2008 13:36:41 -0500 (CDT), Jon Ciesla wrote:

On Wed, 3 Sep 2008 12:10:13 -0500 (CDT), Jon Ciesla wrote:

For example, why games data depend on binaries?
So that if we try to upgrade the version of the binaries and not the
data,
it will fail.
Unconvincing.

Why? Because the game program pkg could require a specific version of
the data pkg to achieve the same. If game version gets bumped, dep
would break, since you would need to update data pkg, too. Game requires
compatible data. So far so good.

However, if the data pkg requires the game pkg (versioned! or else it
would not be strict enough for your needs), this only increases the
risk that you need to bump'n'rebuild the data pkg if the game version
is increased without needing any changed data. It's a superfluous
dependency that only tries to enhance "yum remove" a bit.
How?  For game data, the convention is to require on name and version, but
not release.  If new data is required, it will change the version.  If
not, we only increment the binary rpm's release, so the data rpm matches
on version and needs no rebuild.

game-0.8  Requires  game-data = 0.8
game-data-0.8  Requires  game    (which version? and why?)

Case 1) game-data-0.8 Requires game = 0.8
What happens if game-1.0 is released with unchanged game-data?
Then you need to update game-data for nothing else than the broken dep.

Case 2)
game-data-0.8  Requires  game
No version. Hence no dep breakage in all cases where you may update game
without updating game-data. Instead, a strict dependency is installed
in pkg game:  game-%{version}  Requires  game-data = %{SOME_version}
Here you can control the game-data version within pkg "game".


PLease take an actual look at game spec files before making up all kinds of BS, its really easy:

game Requires game-data = %{needed_data_version}
game-data Requires game >= %{first game version which uses this data}

Its as simple as that, as for this merely working around yum's broken remove, well here we can as there is a 1 on 1 relation, I agree there are other cases where deps get sucked in by an install and not removed by a remove. The fact that those other cases exist is not a good reason to not fix things for games.

Game <-> data is a one on one relation, the Requires reflect that, nothing to see here move along.

Regards,

Hans


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