创建对采用自我的方法的引用的集合的惯用方式是什么? [英] What is the idiomatic way to create a collection of references to methods that take self?

问题描述

我正在尝试将Python脚本转换为Rust，作为一种学习体验，并使该工具更快并缩小代码/可执行文件的大小.

I am trying to convert a Python script into Rust as a learning experience and to make the tool faster and shrink the size of the code/executable.

我当前正在尝试转换一个部分，该部分创建一个对self方法的引用列表.现在，我了解到没有一种方法可以为方法绑定 self 变量，必须使用闭包并关闭将调用该方法的对象.但是，当您创建一个闭包时，它会被分配一个唯一的匿名类型，因此我认为如果不对它们进行装箱，就无法创建一个 Vec 或闭包数组，这可能是可行的方法，但是具有一些不必要的开销.

I'm currently trying to convert a section that creates a list of references to methods on self. Now I've learned that there isn't a way to bind the self variable for a method, one has to use a closure and close over the object that the methods will be called on. However when you create a closure it gets assigned a unique anonymous type, so I don't think I can create a Vec or array of closures without boxing them, which might be the way to go, but has some overhead that might not be necessary.

我想知道的是，不是通过Python告知的方法引用列表的设计，还有一种更生锈的方法来做到这一点而不与类型系统作斗争吗?

What I'm wondering is, instead of the Python informed design of a list of method references, is there a more Rusty way to do this that doesn't fight the type system?

self.dataProcessors = []
if(self.dataMode) :
    self.dataProcessors.append(self._processData_)
if(self.csvOn):
    self.dataProcessors.append(self._processData_CSV_)

推荐答案

老实说，我不确定是否有一种 rusty 的方法，但是，是的，您可以使用相同的方法就像在Python中一样:

To be honest, I’m not sure about a more rusty way, but, yes, you can do it the same way as in Python:

struct Data;

impl Data {
    fn foo(&self) {
        println!("foo!");
    }
    fn bar(&self) {
        println!("bar!");
    }
}

fn main() {
    let x: Vec<fn(&Data) -> ()> = vec![Data::foo, Data::bar];

    let data = Data;
    for f in x {
        f(&data);
    }
}

请注意，这与Python中的工作原理完全一样:您无需保留 self ，而是将其显式传递为now-function的第一个参数，该参数曾经是方法.

Note that this works exactly like in Python: instead of keeping self, you explicitly pass it as the first argument of the now-function which used to be a method.

由于不需要存储任何值(如果使用闭包，则将是必需的)，因此基本上您只拥有一个函数指针(类型为 fn(& Data)->()，也就是函数类型，它采用 Data 并返回单位)，因此它的大小是已知的，您不需要装箱.

Since there is no need to store any values (which would be necessary if you went with closures), basically all you have is a function pointer (of type fn(&Data) -> (), which is, well, the type of functions that take Data and return unit), so its size is known and you don’t need boxing.

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