依赖和解析

当您在 Package Manager 窗口中工作时，可以安装来自多个来源的包（注册表，本地文件夹或者 tarball 以及 Git URL）。然而，虽然 Package Manager 从这些源无缝安装包，但它首先必须进行一系列计算来决定安装哪个版本，以及安装其他哪些包和版本来支持它。

Direct dependencies

When you select a package version to install through the Package Manager window, you are adding a “dependency” to your project manifest. This is a declaration that you need a specific version of a particular package in order for the project to work. To add a dependency to your project, you add a reference to the package and version in the form package-name@package-version to the dependencies property of the <project-root>/Packages/manifest.json file. These are called “direct” dependencies because your project directly depends on them.

Indirect dependencies

Packages can also require other packages in order to work. These are called “indirect”, or transitive, dependencies. The package developer adds these to the dependencies property of the package manifest file during development (<package-root>/package.json). For example, in the diagram below, the alembic@1.0.7 package has a dependency on the timeline@1.0.0 package, so the timeline package is an “indirect ”dependency. On the other hand, the project has dependencies on the cinemachine@2.6.0 and alembic@1.0.7 packages, so those are both “direct” dependencies.

Version overrides

When you add a package version as a dependency, that version is not necessarily the version that the Package Manager installs, because it has to consider all of the dependencies in your project, whether direct or indirect. For example, in this case, the XR Plugin Management package requested was version 4.0.3, but the installed version is actually version 4.0.6 because another package depended on the higher version, as indicated in the information message (B):

Dependency graph

The Package Manager can only install one package version at a time, so it has to construct a dependency graph, which is a list of every direct and indirect dependency for the project. The dependency graph determines which version of each package to install.

Lock file

When the Package Manager successfully resolves all version conflicts, it saves the resolution in a lock file to ensure determinism (so that the same packages are reliably installed every time), and to reduce the amount of time and resources it takes to compute the dependency graph again.