Extend julia module

General Usage
,
1

Hi.
I try to understand modules in julia.
And cant figure out how to extend julia module.

Suppose i have a module:

module Test 
   t :: Float64 = 0
end

how to add new function or variable to the module from another file (or even file with declared module)?

New module declaration will override the previous.

Thanks

2

Let’s say you have a module Foo in file Foo.jl

module Foo
foo() = "hello!" 
end

And you’d like to add more to the module. The most common way is to include another file, for example bar.jl

module Foo
include("bar.jl")
foo() = "hello!" 
end

Then you can place code in bar.jl

bar(name) = "hello $name"
3

Thanks for response!

So i should modify module directly to extend?
No option like c++ namespaces. In REPL i will owerwrite module each time when i add something?

4

From what I know yes, you have to enclose everything between module MODULE_NAME and its corresponding end.

5

It’s not clear what your use case is but one possible answer is that you can eval new things into an existing module.

julia> module Test
       f() = 1
       end
Main.Test

julia> @eval Test begin
       g() = 2
       end
g (generic function with 1 method)

julia> Test.f()
1

julia> Test.g()
2
4 Likes
6

Another way to extend a module from outside is multiple dispatch, that is, adding new methods for functions that are defined inside that module

4 Likes
7

You cannot introduce new values and functions to a module’s namespace externally without an @eval solution like @GunnarFarneback proposed, which sidesteps the issue because it evaluates the code within the module Test.

There is a standard way to extend a module in a somewhat restricted way: add methods to an existing function (what @gdalle mentioned).

julia> module A
       greeting() = "hello"
       end
Main.A

julia> A.greeting()
"hello"

julia> A.greeting(name) = "hello $name" 

julia> A.greeting("Sergey")
"hello Sergey"
3 Likes
8

Thank for examples!