Blockers abuse

I’ve already written about some of the differences between my and Patrick’s tinderboxes, one of which is that my tinderbox does not only install one package, but tries to install all of them at once. This is a necessity for me to have enough material to work on with my library collisions script, and still have so many side effects that makes it funny to work with.

The first problem is that sometimes packages don’t get merged together because of file collisions, which most of the time are caused by packages that install commands with name too generic, and some other times because they regenerate files that should not be present in the final image (like iconv’s charset.alias that gets generated on Gentoo/FreeBSD systems with no good reason at all).

The second problem derives from the way the first problem is handled. When two packages install a file with the same name, rather than renaming one of them or both, it’s customary to actually “fix” the problem by adding blockers to each of the two packages so that they cannot get installed together. While it’s certainly better to have it expressed that way rather than having the merge to fail after the compilation and install phases, it’s not really a solution since it still disallows having the two packages on the same system. While this is acceptable for packages like the different GhostScript implementations that apply for the same task, this is not much of a solution when the packages are entirely independent one from the other and have very different tasks.

I also have found one particular package (pnet) which had a very funky solution to the collision between that and boehm-gc, considering that it was installing a private copy of that. Obviously this was not the proper fix by a mile’s look.

If you have two packages that block each other you have a few different ways to deal with that; if they provide the same function, you might as well install them with a prefix and then write an eselect module to choose between one or the other (which is something that ghostscript could very well be doing); if they only install executables with generic name, they might be changed to prefix the command name with the package name. But sometimes these commands are not to be used by the users at all, and are rather internal commands used by the scripts for processing; in those cases, it would be a nice idea to make those get into /usr/libexec/$PN/ so that they are taken out of the users’ path, and won’t collide one with the other.

While dealing with packages that install colliding files is not so easy, there is need for developers to deal with them in a less “works for me” way, and think more of the general picture, as it is, there are enough packages in the tree that blocks each other with no real good reason, and this is upsetting.

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