Modules

June 8, 2021

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Modules help organize code that can be easily used in another program. The MyModule shown below is an example of a user defined module which includes functions from the funcA and funcB files. For this example the module and its associated files are contained in a folder called MyModule.

# Folder structure for the example module and associated files
MyModule
|- funcA.jl
|- funcB.jl
|- MyModule.jl

# MyModule.jl
module MyModule

include("funcA.jl")
include("funcB.jl")

export myfuncA

end

# funcA.jl
function myfuncA()
    println("Say hello from function A")
end

# funcB.jl
function myfuncB()
    println("Say hello from function B")
end

Two approaches to using a module are demonstrated below. The first approach imports the module with the import mechanism. This brings only the module name into the global scope. Functions associated with the module are accessed with dot notation.

# modules_import.jl

# Load the module file
include("MyModule/MyModule.jl")

# Import the module
import .MyModule

# Use the module functions
MyModule.myfuncA()
MyModule.myfuncB()

julia> modules_import.jl
Say hello from function A
Say hello from function B

The second approach loads the module with the using mechanism. This brings the module name and the exported elements of the module into the global scope.

# modules_using.jl

# Load the module
include("MyModule/MyModule.jl")

# Use the module and its exported function
using .MyModule

# Use the exported function
myfuncA()

# Use a function from the module
MyModule.myfuncB()

julia> modules_using.jl
Say hello from function A
Say hello from function B