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Curiosity
Curiosity

Reputation: 139

Julia: How can I explore all the variables of file A into file B?

I have a couple of questions regarding Julia. I did some online digging but couldn't find any answer. If I have a file nameA.jl which has a whole lot of variables (for example, physical constants such as a mass of the proton), how can I easily export/call all those variables when I need to use in another file (i.e., nameB.jl).

Second, what is the best way to create some sort of "global" variable through "class" (I know Julia does not have the class concept similar to Python) or another mean, so I can access easily to any other file in the project and modify as I need.

I did try to get these answers from google but couldn't find any help.

Thank you

Upvotes: 5

Views: 1002

Answers (1)

Jeffrey Sarnoff
Jeffrey Sarnoff

Reputation: 1757

To your first question:

PhysicalConstants.jl

module PhysicalConstants

export fine_structure_constant, proton_electron_massratio

const fine_structure_constant   = 7.2973525664e-3 
const proton_electron_massratio = 1836.15267247

end # module

UsePhysicalConstants.jl

 importall PhysicalConstants

 this = fine_structure_constant * proton_electron_massratio

 # 13.399053416751173

As I understand your second question:

ChangeableValues.jl

module ChangeableValues

export changeable_value, change_value, value

type Changeable{T}
   value::T
end

typeof_value{T}(x::Changeable{T}) = T
value{T}(x::Changeable{T}) = x.value

# changeable_value is const for speed
# changeable_value.value is not const
const changeable_value = Changeable(0)

function change_value{T}(new_value::T)
    if T == typeof_value(changeable_value)
        changeable_value.value = new_value
    else
        throw(TypeError())
    end
    return nothing
end


end # module

UseChangeableValue.jl

   import ChangeableValues: changeable_value, change_value, value

   println("value = ", value(changeable_value)) # 0
   change_value(1)
   println("value = ", value(changeable_value)) # 1
   change_value(2)
   println("value = ", value(changeable_value)) # 2

   # it remains 2 when imported elsewhere until it is changed again

Upvotes: 3

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