Can someone please explain the `lib` directory?

[mkitti]

I think this lib directory is more convention than anything else. HDF5.jl has a filters directory containing filter sub-packages.

Perhaps the larger explanation that you are looking for is regarding subdirectory packages.

Usage of subdirectories to store multiple packages in a single repo

According to Registrator.jl#287 and Pkg.jl#1422 merged pull requests, several packages can now be organized as subdirectories of a single repo. However, I have not been able to found any detailed docs, which would explain how to use this new functionality. As a result, I would like to ask a number of questions here, on discourse. How are the subdirectories supposed to be organized? Must each of the subdirectories have the normal package structure with Project.toml, Manifest.toml, ./src, ./test…

Unlike modules in the src directory, these other folders are packages in their own right. They have their own Project.toml with an UUID. They just happen to be housed within the same git repository as the parent package.

Pkg does not have an automatic way of looking into a lib directory. One could add the lib directory as a place to load packages from via the environment variable JULIA_LOAD_PATH or the Julia variable Base.LOAD_PATH.

The way HDF5.jl loads up the subpackages is via Pkg.develop or ]dev which allows you specify a local file system path to a package.

JuliaIO/HDF5.jl/blob/7999d1a261cb1c950f026946b4405686281636da/test/runtests.jl#L4-L8

ArrayInterface.jl seems to do something similar:

JuliaArrays/ArrayInterface.jl/blob/cb39428caa0a548f727e8f8e485e0d85d6f1a7de/test/runtests.jl#L5-L8

Pkg.develop will add these packages to the project’s Manifest.toml which will remember the relative paths. However, the Manifest.toml is not usually tracked by git for a library package like those you mentioned.