Scope of variable defined in included file in Julia - scope

Question

I have an input file where some variables are defined. For each iteration in a loop, I would like to read the file, update the values of some of the variables, then run calculations.
I have an input file called input.jl with
myval=1
Then I have a file myscript.jl with the following commands
for i=1:2
include("input.jl")
println(myval)
myval=2
end
If I run the file (julia myscript.jl), I get an error that myval is not defined. If I comment out the third or fourth lines, then it runs with no problem. If I remove the for loop, the three lines run with no problem. How can I read myval from input.jl, use it, then update its value during each iteration of the loop?

Answer 1

Unfortunately, it seems that the include function executes things at global scope, and then continues from where it left off. So if you're trying to dynamically include new variables into local scope, this is not the way to do it.
You can either introduce the variable at global scope first so that the function has access to it, and therefore the assignment will work (but, be aware that the variable will be updated at the global scope).
or
you can cheat by wrapping your input file into a module first. You still need to call the variable by its name, and you will get warnings about updating the module, but this way you can update your local variable dynamically at least, without needing that variable at global scope:
# in input.jl
module Input
myval = 1;
end
# in your main file
for i=1:2
include("input.jl")
myval = Input.myval;
println(myval)
myval=2
end
or
you could add a separate process and offload the calculation to its global scope, and retrieve it to your current process locally, e.g.
# in file input.jl
myval = 1
# in main file
addprocs(1);
for i=1:2
myval = remotecall_fetch(() -> (global myval; include("input.jl"); myval), 2);
println(myval)
myval=2
end