# Can't Get Implicit Package Directories to Work

**URL:** <https://discourse.julialang.org/t/cant-get-implicit-package-directories-to-work/116525>\
**Category:** Package Management\
**Tags:** question\
**Created:** [July 2, 2024, 1:54pm UTC](https://discourse.julialang.org/t/cant-get-implicit-package-directories-to-work/116525 "2024-07-02T13:54:15Z")\
**Posts on this page:** 7\
**Page:** 1

<div class="post-metadata">

**Author:** ![Satvik](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/satvik/32/20486_2.png) [@Satvik](https://discourse.julialang.org/u/Satvik)\
**Post date:** [July 2, 2024, 1:54pm UTC](https://discourse.julialang.org/t/cant-get-implicit-package-directories-to-work/116525/1 "2024-07-02T13:54:15Z")

</div>

I’m trying to create multiple packages in one repository following the implicit package directories method outlined here: [Code Loading · The Julia Language](https://docs.julialang.org/en/v1/manual/code-loading/#Package-directories)

The ultimate goal is to split our large single-package codebase into multiple packages on the same monorepo, in order to reduce precompilation times which are currently ~100s with any change.

So I’ve tried this structure:

```julia
├── PackageA
│ └── src
│ └── PackageA.jl
└── TopLevel
    ├── Project.toml
    └── src
        └── TopLevel.jl

```

This works fine:  
`julia> Pkg.develop(path="TopLevel/")`

But if I try to develop `PackageA`, I get an error message because there’s no `Project.toml` file:

```julia
julia> Pkg.develop(path="PackageA")
ERROR: could not find project file (Project.toml or JuliaProject.toml) in package at `PackageA` maybe `subdir` needs to be specified
Stacktrace:
  [1] pkgerror(msg::String)
    @ Pkg.Types /Applications/Julia-1.10.app/Contents/Resources/julia/share/julia/stdlib/v1.10/Pkg/src/Types.jl:70
  [2] resolve_projectfile!(env::Pkg.Types.EnvCache, pkg::Pkg.Types.PackageSpec, project_path::String)
    @ Pkg.Types /Applications/Julia-1.10.app/Contents/Resources/julia/share/julia/stdlib/v1.10/Pkg/src/Types.jl:860
  [3] handle_repo_develop!(ctx::Pkg.Types.Context, pkg::Pkg.Types.PackageSpec, shared::Bool)
    @ Pkg.Types /Applications/Julia-1.10.app/Contents/Resources/julia/share/julia/stdlib/v1.10/Pkg/src/Types.jl:629
  [4] handle_repos_develop!(ctx::Pkg.Types.Context, pkgs::Vector{Pkg.Types.PackageSpec}, shared::Bool)
    @ Pkg.Types /Applications/Julia-1.10.app/Contents/Resources/julia/share/julia/stdlib/v1.10/Pkg/src/Types.jl:705
  [5] develop(ctx::Pkg.Types.Context, pkgs::Vector{Pkg.Types.PackageSpec}; shared::Bool, preserve::Pkg.Types.PreserveLevel, platform::Base.BinaryPlatforms.Platform, kwargs::@Kwargs{io::Base.TTY})
    @ Pkg.API /Applications/Julia-1.10.app/Contents/Resources/julia/share/julia/stdlib/v1.10/Pkg/src/API.jl:214
  [6] develop(pkgs::Vector{Pkg.Types.PackageSpec}; io::Base.TTY, kwargs::@Kwargs{})
    @ Pkg.API /Applications/Julia-1.10.app/Contents/Resources/julia/share/julia/stdlib/v1.10/Pkg/src/API.jl:159
  [7] develop(pkgs::Vector{Pkg.Types.PackageSpec})
    @ Pkg.API /Applications/Julia-1.10.app/Contents/Resources/julia/share/julia/stdlib/v1.10/Pkg/src/API.jl:148
  [8] develop
    @ /Applications/Julia-1.10.app/Contents/Resources/julia/share/julia/stdlib/v1.10/Pkg/src/API.jl:146 [inlined]
  [9] develop(; name::Nothing, uuid::Nothing, version::Nothing, url::Nothing, rev::Nothing, path::String, mode::Pkg.Types.PackageMode, subdir::Nothing, kwargs::@Kwargs{})
    @ Pkg.API /Applications/Julia-1.10.app/Contents/Resources/julia/share/julia/stdlib/v1.10/Pkg/src/API.jl:176
 [10] top-level scope
    @ REPL[7]:1

```

This happens with every variation I could think of trying, e.g. `julia> Pkg.develop(path="."; subdir="PackageA")`, and activating/not activating the `TopLevel` project.

Am I missing something? Does `develop` require a `Project.toml`? If so, how can you use packages without a `Project.toml`?

---

<div class="post-metadata">

**Author:** ![adienes](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/adienes/32/37459_2.png) [@adienes](https://discourse.julialang.org/u/adienes)\
**Post date:** [July 2, 2024, 2:09pm UTC](https://discourse.julialang.org/t/cant-get-implicit-package-directories-to-work/116525/2 "2024-07-02T14:09:26Z")

</div>

> [@Satvik](#):
>
> how can you use packages without a `Project.toml`?

I’m not sure that this is possible. you might have better luck giving each subpackage it’s own `Project.toml`, and then the top level `Project.toml` adds `A, B, C ...`

---

<div class="post-metadata">

**Author:** ![Satvik](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/satvik/32/20486_2.png) [@Satvik](https://discourse.julialang.org/u/Satvik)\
**Post date:** [July 2, 2024, 3:00pm UTC](https://discourse.julialang.org/t/cant-get-implicit-package-directories-to-work/116525/4 "2024-07-02T15:00:16Z")

</div>

> A package is defined by a Project.toml. There’s no package otherwise.

The documentation I linked definitely states otherwise, and gives an example of a package structure where not every package has a `Project.toml`. Is it just wrong/out of date?

---

<div class="post-metadata">

**Author:** ![Satvik](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/satvik/32/20486_2.png) [@Satvik](https://discourse.julialang.org/u/Satvik)\
**Post date:** [July 2, 2024, 3:03pm UTC](https://discourse.julialang.org/t/cant-get-implicit-package-directories-to-work/116525/5 "2024-07-02T15:03:56Z")

</div>

Yeah, I can get it to work with individual `Project.toml` files, but that means maintaining ~5 sets of dependencies, which I was hoping to avoid since these are all essentially subpackages of the same environment.

---

<div class="post-metadata">

**Author:** ![GunnarFarneback](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/gunnarfarneback/32/1827_2.png) [@GunnarFarneback](https://discourse.julialang.org/u/GunnarFarneback)\
**Post date:** [July 2, 2024, 3:47pm UTC](https://discourse.julialang.org/t/cant-get-implicit-package-directories-to-work/116525/6 "2024-07-02T15:47:57Z")

</div>

> [@Satvik](#):
>
> Is it just wrong/out of date?

If the file structure works with Julia 1.0 but not with 1.10, I would suspect that the documentation is out of date and needs an issue.

---

<div class="post-metadata">

**Author:** ![fatteneder](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fatteneder/32/33991_2.png) [@fatteneder](https://discourse.julialang.org/u/fatteneder)\
**Post date:** [July 2, 2024, 4:05pm UTC](https://discourse.julialang.org/t/cant-get-implicit-package-directories-to-work/116525/7 "2024-07-02T16:05:24Z")

</div>

From the linked page:

> A few general rules to note:  
> …  
> 2. A package with a project file cannot depend on one without a project file since packages with project files can only load packages in graph and packages without project files do not appear in graph.

* * *

I am waiting for the upcoming `workspace` feature in `Pkg.jl`, which will hopefully simplify the organization of such mono repos.

* * *

This discussion here might also be of interest to you: [Create an implicit environment with package directories](https://discourse.julialang.org/t/create-an-implicit-environment-with-package-directories/109207)

---

<div class="post-metadata">

**Author:** ![Satvik](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/satvik/32/20486_2.png) [@Satvik](https://discourse.julialang.org/u/Satvik)\
**Post date:** [July 2, 2024, 4:37pm UTC](https://discourse.julialang.org/t/cant-get-implicit-package-directories-to-work/116525/8 "2024-07-02T16:37:18Z")

</div>

Oh, workspace looks like exactly what I want! Maybe I’ll wait until 1.12 then.