# How to append the docstring of a type or function in the upstream package in a downstream package

**URL:** <https://discourse.julialang.org/t/how-to-append-the-docstring-of-a-type-or-function-in-the-upstream-package-in-a-downstream-package/113418>\
**Category:** General Usage\
**Tags:** question, documentation, docstring\
**Created:** [April 24, 2024, 3:09am UTC](https://discourse.julialang.org/t/how-to-append-the-docstring-of-a-type-or-function-in-the-upstream-package-in-a-downstream-package/113418 "2024-04-24T03:09:05Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![kimikage](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kimikage/32/14534_2.png) [@kimikage](https://discourse.julialang.org/u/kimikage)\
**Post date:** [April 24, 2024, 3:09am UTC](https://discourse.julialang.org/t/how-to-append-the-docstring-of-a-type-or-function-in-the-upstream-package-in-a-downstream-package/113418/1 "2024-04-24T03:09:05Z")

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As an example, consider developing a downstream package like `SpecificFoo.jl` using upstream packages which provide APIs like `FooBase.jl`/`FooCore.jl`.

We can write a docstring for the method defined in the downstream package, if it is a method of _public_ function.  
**Edit:** e.g.

```julia
"something_public(::FooCore.AbstractFoo)" something_public # in FooCore.jl

"something_public(::SpecificFoo.Foo)" something_public(::SpecificFoo.Foo) # in SpecificFoo.jl

```

However, with sophisticated APIs, the internal implementation may be hidden from the end-users.  
**Edit:** e.g.

```julia
get_most_pretty_foo(::AbstractArray{T}) where {T<:AbstractFoo} # public API for end-users

is_less_pretty(::T1, ::T2) where {T1<:AbstractFoo,T2<:AbstractFoo} # internal API for package developers

```

So, I believe there are demands to append docstrings to functions or types in upstream packages rather than methods in downstream packages (i.e. to write appendices).

From the current implementation of `Docs`, it would be technically possible, but it is “piracy”.  
This means that it would be troublesome in the doc system if both `SpecificFoo.jl` and `YetAnotherFoo.jl` try to append docstrings.  
(On the other hand, users will not be so troubled if docstrings are not overwritten.)

What are the best practices in the supposed case?

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<div class="post-metadata">

**Author:** ![kimikage](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kimikage/32/14534_2.png) [@kimikage](https://discourse.julialang.org/u/kimikage)\
**Post date:** [April 24, 2024, 6:02am UTC](https://discourse.julialang.org/t/how-to-append-the-docstring-of-a-type-or-function-in-the-upstream-package-in-a-downstream-package/113418/3 "2024-04-24T06:02:43Z")

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FWIW, what I’m looking for is a little like `Base.Experimental.register_error_hint`.  
[https://docs.julialang.org/en/v1/base/base/#Base.Experimental.register\_error\_hint](https://docs.julialang.org/en/v1/base/base/#Base.Experimental.register_error_hint)

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<div class="post-metadata">

**Author:** ![kimikage](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kimikage/32/14534_2.png) [@kimikage](https://discourse.julialang.org/u/kimikage)\
**Post date:** [April 28, 2024, 9:41am UTC](https://discourse.julialang.org/t/how-to-append-the-docstring-of-a-type-or-function-in-the-upstream-package-in-a-downstream-package/113418/4 "2024-04-28T09:41:06Z")

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Well, this is not much demand and it doesn’t seem like it would be a good idea to confuse the docsystem.