是否可以从 Julia 中的覆盖函数中调用重载函数? [英] Is it possible to call an overloaded function from overwriting function in Julia?

问题描述

问题如下:

我有一个抽象类型 MyAbstract 和派生的复合类型 MyType1 和 MyType2:

I have an abstract type MyAbstract and derived composite types MyType1 and MyType2:

abstract MyAbstract

type MyType1 <: MyAbstract
    somestuff
end

type MyType2 <: MyAbstract
    someotherstuff
end

我想为 MyAbstract 类型的对象指定一些一般行为，所以我有一个函数

I want to specify some general behaviour for objects of type MyAbstract, so I have a function

function dosth(x::MyAbstract)
    println(1) # instead of something useful
end

这种一般行为对于 MyType1 来说已经足够了，但是当使用 MyType2 类型的参数调用 dosth 时，我希望发生一些额外的事情是特定于 MyType2 的，当然，我想重用现有代码，所以我尝试了以下方法，但没有奏效:

This general behaviour suffices for MyType1 but when dosth is called with an argument of type MyType2, I want some additional things to happen that are specific for MyType2 and, of course, I want to reuse the existing code, so I tried the following, but it did not work:

function dosth(x::MyType2)
    dosth(x::MyAbstract)
    println(2)
end

x = MyType2("")
dosth(x) # StackOverflowError

这意味着 Julia 有一段时间没有意识到我试图将 x 视为它的超类型".

This means Julia did not recognize my attempt to treat x like its "supertype" for some time.

是否可以从 Julia 的覆盖函数中调用重载函数?我该如何优雅地解决这个问题?

Is it possible to call an overloaded function from the overwriting function in Julia? How can I elegantly solve this problem?

推荐答案

您可以使用调用函数

You can use the invoke function

function dosth(x::MyType2)
    invoke(dosth, (MyAbstract,), x)
    println(2)
end

使用相同的设置，这会给出以下输出而不是堆栈溢出:

With the same setup, this gives the follow output instead of a stack overflow:

julia> dosth(x)
1
2

可以在这里找到关于替换或改进invoke界面的讨论.我的建议将使语法非常接近您在问题中写的内容:

Discussion can be found here on replacing or improving the interface to invoke. My proposal would make the syntax very close to what you wrote in your question:

function dosth(x::MyType2)
    @invoke dosth(x::MyAbstract)
    println(2)
end

如果您对比invoke"更直观的名称有什么想法，请在下方发表评论.

If you have any thoughts on what a more intuitive name than "invoke" would be, please post a comment below.

这篇关于是否可以从 Julia 中的覆盖函数中调用重载函数?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！