Trouble creating Package Extension

General Usage
1

I’m trying to create a package extension (see 5. Creating Packages · Pkg.jl) for a package I’ve created, triggered by the Plots package.

I have the following in my package’s Project.toml file:

[extensions]
Plotting = "Plots"

and a file ext/Plotting.jl with the following:

module Plotting
using Plots
   ... functions
end # module

But then if I just try to launch a Julia session in this project, I get an error:

% julia --project=.
ERROR: LoadError: Trigger Plots for extension Plotting not found in project
Stacktrace:
  [1] error(s::String)
    @ Base ./error.jl:35
  [2] Pkg.API.Precompilation.ExplicitEnv(envpath::String)
    @ Pkg.API.Precompilation ~/.julia/juliaup/julia-1.10.8+0.aarch64.apple.darwin14/share/julia/stdlib/v1.10/Pkg/src/precompilation.jl:91
  [3] Pkg.API.Precompilation.ExplicitEnv()
    @ Pkg.API.Precompilation ~/.julia/juliaup/julia-1.10.8+0.aarch64.apple.darwin14/share/julia/stdlib/v1.10/Pkg/src/precompilation.jl:33
  [4] _precompilepkgs(pkgs::Vector{String}, internal_call::Bool, strict::Bool, warn_loaded::Bool, timing::Bool, _from_loading::Bool, configs::Vector{Pair{Cmd, Base.CacheFlags}}, io::IOContext{IO}, fancyprint::Bool, manifest::Bool)
    @ Pkg.API.Precompilation ~/.julia/juliaup/julia-1.10.8+0.aarch64.apple.darwin14/share/julia/stdlib/v1.10/Pkg/src/precompilation.jl:352
  [5] #precompilepkgs#5
    @ ~/.julia/juliaup/julia-1.10.8+0.aarch64.apple.darwin14/share/julia/stdlib/v1.10/Pkg/src/precompilation.jl:333 [inlined]
  [6] (::Pkg.API.var"#225#226"{Bool, Bool, Bool, Bool, Bool, Vector{Pkg.Types.PackageSpec}})()
    @ Pkg.API ~/.julia/juliaup/julia-1.10.8+0.aarch64.apple.darwin14/share/julia/stdlib/v1.10/Pkg/src/API.jl:1090
  [7] activate(f::Pkg.API.var"#225#226"{Bool, Bool, Bool, Bool, Bool, Vector{Pkg.Types.PackageSpec}}, new_project::String)
    @ Pkg.API ~/.julia/juliaup/julia-1.10.8+0.aarch64.apple.darwin14/share/julia/stdlib/v1.10/Pkg/src/API.jl:1315
  [8] precompile(ctx::Pkg.Types.Context, pkgs::Vector{Pkg.Types.PackageSpec}; internal_call::Bool, strict::Bool, warn_loaded::Bool, already_instantiated::Bool, timing::Bool, _from_loading::Bool, kwargs::@Kwargs{io::Base.TTY})
    @ Pkg.API ~/.julia/juliaup/julia-1.10.8+0.aarch64.apple.darwin14/share/julia/stdlib/v1.10/Pkg/src/API.jl:1088
  [9] precompile(pkgs::Vector{Pkg.Types.PackageSpec}; io::Base.TTY, kwargs::@Kwargs{_from_loading::Bool})
    @ Pkg.API ~/.julia/juliaup/julia-1.10.8+0.aarch64.apple.darwin14/share/julia/stdlib/v1.10/Pkg/src/API.jl:159
 [10] precompile
    @ ~/.julia/juliaup/julia-1.10.8+0.aarch64.apple.darwin14/share/julia/stdlib/v1.10/Pkg/src/API.jl:147 [inlined]
 [11] #precompile#114
    @ ~/.julia/juliaup/julia-1.10.8+0.aarch64.apple.darwin14/share/julia/stdlib/v1.10/Pkg/src/API.jl:146 [inlined]
 [12] #invokelatest#2
    @ ./essentials.jl:894 [inlined]
 [13] invokelatest
    @ ./essentials.jl:889 [inlined]
 [14] _require(pkg::Base.PkgId, env::String)
    @ Base ./loading.jl:2033
 [15] __require_prelocked(uuidkey::Base.PkgId, env::String)
    @ Base ./loading.jl:1882
 [16] #invoke_in_world#3
    @ ./essentials.jl:926 [inlined]
 [17] invoke_in_world
    @ ./essentials.jl:923 [inlined]
 [18] _require_prelocked(uuidkey::Base.PkgId, env::String)
    @ Base ./loading.jl:1873
 [19] macro expansion
    @ ./loading.jl:1860 [inlined]
 [20] macro expansion
    @ ./lock.jl:267 [inlined]
 [21] __require(into::Module, mod::Symbol)
    @ Base ./loading.jl:1823
 [22] #invoke_in_world#3
    @ ./essentials.jl:926 [inlined]
 [23] invoke_in_world
    @ ./essentials.jl:923 [inlined]
 [24] require(into::Module, mod::Symbol)
    @ Base ./loading.jl:1816
in expression starting at /Users/kwilliams/.julia/config/startup.jl:2
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.10.8 (2025-01-22)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org/ release
|__/                   |

I’m confused by this - I don’t want to add Plots to this project, because it’s an optional dependency, right? What’s the proper way to deal with this?

2

I think you need to add to [weakdeps], Pkg REPL mode’s add needs the -w/--weak flag, or Pkg.add needs the target=:weakdeps keyword argument. That currently doesn’t change the [extensions] for you though, might be a problem with weakdeps not necessarily being a property of extensions: Make add --weak automatically create extension entries · Issue #3549 · JuliaLang/Pkg.jl

1 Like
3

This option doesn’t seem to exist in the REPL for me:

pkg> add --weak Plots
ERROR: option 'weak' is not a valid option

Was this added in 1.11 maybe? I’m on 1.10 with this project.

4

Just realized (as you said) that I can simply add

[weakdeps]
Plots = "91a5bcdd-55d7-5caf-9e0b-520d859cae80"

manually to my Project.toml file, and this seems to work! Thanks. I haven’t tried out the actual extension yet, but this seems to get most things loading.

5

Indeed, you’ll have to edit the file manually before that.

1 Like