Does Julia support static variables with function-scope

Question

In C, one can declare static variables with local function scope (example).

Can something similar be done in Julia?

My use case is declaring sub-functions, but do not want Julia to have to reparse them every time the code executes. Declaring them outside of the function is ugly and gives them higher scope, which I want to avoid.

example:

function foo(x)
    static bar = t -> stuff with t

    ...
    bar(y)
    ...
end

While I could declare bar() outside of foo(), I would prefer bar to only be in the local namespace.

Thank you.

ivarne · Accepted Answer · 2014-07-03 06:47:51Z

16

You can create a new scope around the function, to hold the variable.

let
    global foo
    function bar(t)
        #stuff with t
    end
    y = 2
    function foo(x)
        #...
        bar(y)
        #...
    end
end

Then only foo(x) will be visible to the outside

answered Jul 3, 2014 at 6:47

ivarne

3,8031 gold badge29 silver badges32 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

a06e · Accepted Answer · 2016-04-03 07:07:08Z

5

Based on @ivarne's answer.

let bar = t -> t^2
    global foo
    function foo(x)
        bar(x)
    end
end

But I don't think this is an ideal solution. IMHO it would be better to have a static keyword. The extra block is unwieldy. There is some discussion about this in Julia development:

https://github.com/JuliaLang/julia/issues/15056

https://github.com/JuliaLang/julia/issues/12627

edited Apr 3, 2016 at 7:07

answered Mar 31, 2016 at 9:28

a06e

21.2k36 gold badges106 silver badges185 bronze badges

Comments

kmsquire · Accepted Answer · 2014-07-17 17:21:32Z

4

Note that y needs to be a let variable in @ivarne's answer, or it will overwrite any y in global scope:

julia> y = 4
4

julia> let
           global foo
           function bar(t)
               #stuff with t
           end
           y = 2
           function foo(x)
               #...
               bar(y)
               #...
           end
       end
foo (generic function with 1 method)

julia> y
2

answered Jul 17, 2014 at 17:21

kmsquire

1,49213 silver badges13 bronze badges

Collectives™ on Stack Overflow

Does Julia support static variables with function-scope

3 Answers 3

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related