绑定函数(委托)参数 [英] Bind function (delegate) arguments

问题描述

我正在尝试不使用lambda函数来实现以下目标:

I'm trying to achieve the following without using lambda function:

Func<bool> test = () => RunSomething("test");  <-- This work fine but creates lambda
Func<bool> test = bind(RunSomething, "test"); <-- Bind "test" to RunSomething  

换句话说，我想知道是否有可能以某种方式绑定Function和arguments.
在C ++中，可以使用std :: bind来实现，但是在C#中可以吗?

In other words I'm want to know if it is possible to somehow bind Function and arguments.
It is possible in C++ using std::bind, but is it possible in C# ?

推荐答案

构建这样的方法很容易，但这将使用lambda表达式实现:

Well it's easy to build such a method, but that would use a lambda expression for the implementation:

public Func<TResult> Bind<T, TResult>(Func<T, TResult> func, T arg)
{
    return () => func(arg);
}

同样，对于带有更多参数的函数，有些重载:

And likewise some overloads for functions with more arguments:

public Func<T2, TResult> Bind<T1, T2, TResult>
    (Func<T1, T2, TResult> func, T1 arg)
{
    return t2 => func(arg, t2);
}

public Func<T2, TResult> Bind<T1, T2, T3, TResult>
    (Func<T1, T2, T3, TResult> func, T1 arg)
{
    return (t2, t3) => func(arg, t2, t3);
}

继续执行所需的操作-甚至可以添加方法以在调用中绑定多个参数.

Keep going as far as you want - possibly even adding methods to bind more than one argument in a call.

您可以完成所有这些操作而无需使用lambda表达式，但这将需要更多工作.例如:

You can do all this without a lambda expression, but it would just be more work. For example:

public Func<TResult> Bind<T, TResult>(Func<T, TResult> func, T arg)
{
    return new Binder<T, TResult>(func, arg).Apply;
}

private sealed class Binder<T, TResult>
{
    private readonly T arg;
    private readonly Func<T, TResult> func;

    internal Binder(Func<T, TResult> func, T arg)
    {
        this.func = func;
        this.arg = arg;
    }

    public TResult Apply()
    {
        return func(arg);
    }
}

基本上，这就是编译器会使用lambda表达式自动为您执行的操作，那么为什么要自己做呢?

That's basically what the compiler would do for you automatically with a lambda expression, so why do it yourself?

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