是否可以创建一个宏来实现构建器模式方法? [英] Is it possible to create a macro to implement builder pattern methods?

问题描述

我为我的结构实现了一个构建器模式:

I have a builder pattern implemented for my struct:

pub struct Struct {
    pub grand_finals_modifier: bool,
}
impl Struct { 
    pub fn new() -> Struct {
        Struct {
            grand_finals_modifier: false,
        }
    }

    pub fn grand_finals_modifier<'a>(&'a mut self, name: bool) -> &'a mut Struct {
        self.grand_finals_modifier = grand_finals_modifier;
        self
    }
}

是否可以在 Rust 中为这样的方法创建一个宏来泛化并避免大量重复代码?我们可以使用以下内容:

Is it possible in Rust to make a macro for methods like this to generalize and avoid a lot of duplicating code? Something that we can use as the following:

impl Struct {
    builder_field!(hello, bool);
}     

推荐答案

阅读文档后，我想出了这个代码:

After reading the documentation, I've come up with this code:

macro_rules! builder_field {
    ($field:ident, $field_type:ty) => {
        pub fn $field<'a>(&'a mut self,
                          $field: $field_type) -> &'a mut Self {
            self.$field = $field;
            self
        }
    };
}

struct Struct {
    pub hello: bool,
}
impl Struct {
    builder_field!(hello, bool);
}

fn main() {
    let mut s = Struct {
        hello: false,
    };
    s.hello(true);
    println!("Struct hello is: {}", s.hello);
}

它完全符合我的需要:创建一个具有指定名称、指定成员和类型的公共构建器方法.

It does exactly what I need: creates a public builder method with specified name, specified member and type.

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