Organizing and modularizing your code

Module naming rule

From Ref 1.

Also, it is common to use UpperCamelCase for module names (just like types), and use the plural form if applicable, especially if the module contains a similarly named identifier, to avoid name clashes.

No private method

From Ref 1.

However, since qualified names always make identifiers accessible, this is just an option for organizing APIs: unlike other languages, Julia has no facilities for truly hiding module internals.

import modules

From Ref 1.

import .NiceStuff

This brings only the module name into scope. Users would need to use NiceStuff.DOG, NiceStuff.Dog, and NiceStuff.nice to access its contents. Usually, import ModuleName is used in contexts when the user wants to keep the namespace clean. As we will see in the next section import .NiceStuff is equivalent to using .NiceStuff: NiceStuff.

Test specific dependencies

From Pkg manual we do not need to define separate test project to manage specific test dependencies. This still not well defined as the manual said.

That is, just install package in the project and move the dependency to test as following.

(HelloWorld) pkg> add Markdown

Edit project.toml file from

[deps]
Markdown = "...."

[extra]
Test = "...."

[targets]
test = ["Test"]

[deps]

[extra]
Test = "...."
Markdown = "...."

[targets]
test = ["Test", "Markdown"]

Module, package and environment

Julia	Java	C++	Python
Module	Package	Namespace	Module
Package	JAR	DLL	Package
Environment	Environment	Sandbox or Container	Virtual environment

Julia module is the same concept as C++ namespace and environment in Julia has same meaning in virtual environment in Python.

Using and import

Ref	Statement	What is brought into the scope
1	using Calculator	interest, rate, Calculator.interest, Calculator.rate
2	using Calculator: interest	interest
3	import Calculator	Calculator.interest, Calculator.rate
4	import Calculator: interest	Calculator.interest
4	import Calculator.interest	Calculator.interest

Environment stack

See Ref 2, 3 for more detail

julia> LOAD_PATH
3-element Vector{String}:
"@"
"@v#.#"
"@stdlib"

where @ is the current environment, @v#.# is the default environment for the Julia version that is being in use, and @stdlib is the standard library.

For instance, for including just the current environment we can set the value of this variable as:

$ export JULIA_LOAD_PATH="@"

Then, when we start a Julia session the default option will be the current environment:

julia> LOAD_PATH
1-element Vector{String}:
"@"

One can also modify the LOAD_PATH directly on the julian prompt with the following functions:

julia> empty!(LOAD_PATH)        # this will clean out the path
julia> push!(LOAD_PATH, "@")    # it will add the current environment