在Julia中，是否有一种方法可以将变量从本地范围传递到封闭的本地范围? [英] In Julia, is there a way to pass a variable from a local scope to the enclosing local scope?

问题描述

我正在编写一些Julia代码，并包装在一个函数中以提高性能.我需要将在循环中创建的变量传递给外部循环，但是出于性能原因，我想避免使用全局变量:

I am writing some Julia code, wrapped in a function for performance. I need to pass a variable created in a loop to an outer loop but would like to avoid globals for performance reasons:

function f()
    for i=1:1
        for j=1:1
        a=2
        end
    println(a)
    end
end
f()

由于i循环的范围不了解变量 a ，因此会引发错误.首先在有问题的范围内定义 a :

This throws an error since the scope of the i-loop does not know about the variable a. Definining a first within the scope in question works:

function f()
    for i=1:1
    a=0
        for j=1:1
        a=2
        end
    println(a)
    end
end
f()

不过，我对这种解决方案并不满意，因为它需要预定义我要传递的每个变量.没有直接方法将变量传递到封闭范围吗?

I am not super happy with that solution though, since it requires to pre-define every variable that I want to pass. Is there no direct way to pass the variable to the enclosing scope?

推荐答案

我不认为有直接方法(除了global a = 2您要避免的方法除外).

I don't think there is a direct way (except global a = 2 what you want to avoid).

最接近您想要的是使用local:

The closest to what you want is to use local:

function f()
    for i=1:1
    local a
        for j=1:1
        a=2
        end
    println(a)
    end
end
f()

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