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This problem is frequent among novice Julia programmers and was already asked multiple times in this forum. (But I concede that the search utility of Discourse never finds any useful results, even when I know they exist.) See:
Basically, the rule is: include once and import whenever necessary.
Your topmost module should include all files a single time and you should use import
/using
relative to it (using .MyModule
refers to a module defined in the current module, using ..MyModule
refers to a module define in the parent module, i.e., a sibling module, and you can do something like using ...MyModule.A.B
to go to the parent of the parent and then go down to a specific submodule). In your case, if you include
Useful
and Create
inside Calculate
you want to replace the include("useful.jl")
inside Create
by import ..Useful