> If two things require different versions of a package, those seem like separate projects to me. You may be thinking of packages on the scale of frameworks. F

> If two things require different versions of a package, those seem like separate projects to me. You may be thinking of packages on the scale of frameworks. For example, if you have a Ruby on Rails app that mixes packages from Rails 3 and Rails 5, well sure, then you're in for some serious trouble. But a lot of packages are much more narrow in scope. Rust has a lot of small crates for basic data structures that have their APIs change betweeen versions. So you could end up with your logging package internally depending on some_data_structure=1.2, while your RabbitMQ client library internally depends on some_data_structure=2.3. As long as they do not expose some_data_structure in their API, you will never even notice (except maybe through increased binary size).