krastanov/julia-package-dev

Julia Package Development

Use this skill for package-oriented Julia work: bootstrapping a package, local environments, multi-package workspaces, extensions, and Pkg apps.

Core Workflow

using Pkg

Pkg.activate("./dev")
Pkg.develop(path="./MyPackage.jl")
using MyPackage

Prefer environments over mutating the global default environment.

• Set ENV["JULIA_PKG_SERVER_REGISTRY_PREFERENCE"] = "eager" before Pkg operations in local or CI sessions in this workspace. Use this by default when recent registrations may matter; otherwise just-registered packages can appear to be missing and create false resolution failures.
• Prefer Pkg.test(...) over directly executing test/runtests.jl when validating a package checkout. Treat direct test/runtests.jl execution as a runner-debugging path, not the default validation path.
• Never read or edit Manifest.toml directly. Treat every manifest as generated state owned by Pkg.
• If dependency resolution behaves impossibly, run Pkg.update() and Pkg.resolve() in the relevant environment first. If recurrent issues remain, delete the relevant Manifest.toml file and regenerate it with Pkg.instantiate().
• Read Project.toml when needed, but change dependencies and compat entries only through Pkg APIs such as Pkg.add, Pkg.develop, Pkg.rm, Pkg.free, and Pkg.compat.

Multi-Repo Rule

• In a workspace with sibling repos, if compat or registry resolution blocks testing, first Pkg.develop(path=...) the local dependency checkouts already present, preferably on their current master/main.
• Do this before chasing registry lag or editing compat blindly.

Pick a Topic

• Pkg commands and dependency management: references/pkg-commands.md
• Interactive debugging and exploration: references/debugging.md
• Multi-package development and release flow: references/multipackage-git-workflow.md
• Package extension patterns: references/extension-patterns.md
• Testing and documenting extensions: references/extension-testing.md
• User-facing extension error hints: references/weakdephelpers.md
• Pkg app scaffolding and CLI patterns: references/pkg-app-patterns.md

Common Tasks

Shared Workspace

using Pkg
Pkg.activate("quantum-dev")
Pkg.develop(path="./QuantumInterface.jl")
Pkg.develop(path="./QuantumSavory.jl")

Notes

• Use julia-tests for test execution and organization.
• Use julia-docs for docs setup and doctests.
• Use julia-comonicon when you need a richer CLI than Pkg apps provide.

Related Skills

• julia-tests
• julia-docs
• julia-scratch