Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Comparison of Programming Language Package Managers

docs.google.com

Post reply on HN
Print view View original

1–10 of 98 posts

Re: Comparison of Programming Language Package Managers

#5

Post by knucklesandwich »

One of the things that I've found to be important for (and generally under-documented by) package managers is resolution strategy.

pip, for instance, eagerly resolves the highest version of a dependency first found in the tree and doesn't backtrack AFAIK [1]. Cargo sounds as though it behaves similarly, but will actually backtrack [2]. I've also seen package managers like 0install that will use SAT solvers to solve dependency constraints [3].

I've found lack of backtracking on conflicts to be frustrating, but I'm curious how the other two (and other conflict resolving strategies) compare in practice.

[1]: https://github.com/pypa/pip/issues/988

[2]: http://doc.crates.io/cargo/core/resolver/index.html

[3]: http://0install.net/solver.html

Re: Comparison of Programming Language Package Managers

#7

Post by steveklabnik »

the_mitsuhiko wrote: post #2

Cargo supports vendoring and enforces semver. Not sure why that document disagrees.

The difference is in the central repository: Elm will compare your types to the previous versions and how the versions diff, and refuse to let you upload a package that makes a backwards incompatible change without bumping the version.

At least, that's my understanding of what they meant.

Re: Comparison of Programming Language Package Managers

#8

Post by haldean »

knucklesandwich wrote: post #5

One of the things that I've found to be important for (and generally under-documented by) package managers is resolution strategy. pip, for instance, eagerly resolves the highest version of a dependency first found in the tree and doesn't backtrack AFAIK [1]. Cargo sounds as though it behaves similarly, but will actually backtrack [2]. I've also seen package managers like 0install that will use SAT solvers to solve d…

pip's lack of backtracking is doubly irritating, because it installs packages as it goes. It would be great if it would fetch all of the required manifests and make sure that the install was going to succeed before it starts spewing stuff everywhere, but instead it will happily back itself into a corner where A->B->C(v1) and A->D->C(v2) conflict and so it leaves the system with A, B and C(v1) installed and prints a nice red stack trace.
Post reply on HN