Best way to extend a type doc string

General Usage
1

Pkg A defines some type Foo, and this includes the declaration of a document string.
Pkg B extends the functionality of Foo objects and wants to extend, not replace, the type’s docstring.

What’s a clean way to do this?

2

“it just works”

julia> module A
           """
           docstring in A
           """
           struct aa end
       end
Main.A

help?> Main.A.aa
  docstring in A


julia> module B
           using Main.A
           """
           docstring in B
           """
           Main.A.aa
       end
Main.B

help?> Main.A.aa
  docstring in A

  ───────────────────────────────────────────────────────────────────────────────────────────────────────

  docstring in B
3

Great. That answers the question that I posed!

But what if I want to do the extension in the same module. That does not “just work”, right?

4

It should just work, much like you can have separate docstring for each method and they all show up

5

It doesn’t seem to work:

"""
line 1
"""
struct Goo end

julia> @doc Goo   
  line 1

# now add post facto:
@doc """line2""" Goo

julia> @doc Goo
   line 2

“line 1” has been replaced.

What am I missing?

6
  1. a docstring is registered in the module where it is defined.
  2. only one docstring in a module is associated with a (function/type, signature) pair
    a. defining another one replaces the incumbent.
  3. a docstring for a bare type has a null signature (i.e., Union{})
    a. constructors can add new docstrings.