Scope of variables in Julia

In this chapter, we will illustrate some variable scoping issues that might not be obvious to all Julia users. A variable can be defined in one of two scopes—either local or global. 

Getting ready

For this recipe, you do not need to install any packages.

Note

In the GitHub repository for this recipe you will find the commands.txt file that contains the presented sequence of Julia commands.

How to do it...

To test how variable scoping works in Julia, follow the steps:

1. Firstly, to illustrate variable scoping in Julia, run the following code:

julia>a, b=1, 2;
​
julia>leta=30, b=40
letb=500
println("inner scope $a $b")
end
println("outer scope $a $b")
end
innerscope30500
outerscope3040
​
julia>println("global scope $a $b")
globalscope12

We can see that with each scoping level (created by a let...end block), the meaning of variables changes. The let statement creates a new scope for variables.

2. Observe the following code:

julia>x=5;
​
julia>let
println(x+1)
end...