本文介绍了从拉姆达EX pressions方法参数得到最终值的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

基本上我希望得到一个所谓的方法是这样的参数值:

  VAR X = 1;
变种一个= 2;
变种B = 3;
DO< HomeController的>(O => o.Save(X,吉米,A + B + 5的Math.sqrt(81)));

公共静态无效走走LT; T>(出pression<作用< T>>除权pression)其中T:控制器
{
  //获取值1,吉米,10,9这里
}
 

解决方案

那么,你需要钻到EX pression,找到 MethodCallEx pression ,再看看参数吧。需要注意的是我们没有的 0 的价值,所以我们必须假设参数的方法不依赖于这一点。此外,我们还在假设拉姆达EX pression仅仅依赖于它是一个 MethodCallEx pression

编辑:好的,这里有一个编辑的版本,它计算参数。但是,假设你的没有的真正使用中的参数拉姆达EX pression参数(这是什么新的对象[1] 约 - 它提供了一个空参数,有效的)

 使用系统;
使用System.Linq.Ex pressions;

类Foo
{
    公共无效保存(INT X,y字符串,INT Z,双D)
    {
    }
}

类节目
{
    静态无效的主要()
    {
        变种X = 1;
        变种一个= 2;
        变种B = 3;
        ShowValues​​<富>(O => o.Save(X,吉米,A + B + 5的Math.sqrt(81)));
    }

    静态无效ShowValues​​< T>(出pression<作用< T>>除权pression)
    {
        VAR通话= EX pression.Body为MethodCallEx pression;
        如果(调用== NULL)
        {
            抛出新的ArgumentException(不是一个方法调用);
        }
        的foreach(前pression在call.Arguments参数)
        {
            LambdaEx pression波长=前pression.Lambda(参数,
                                                        EX pression.Parameters);
            代表D = lambda.Compile();
            对象值= d.DynamicInvoke(新对象[1]);
            Console.WriteLine(GOT值:{0},值);
        }
    }
}
 

basically I want to get the values of the parameters of a called method like this:

var x = 1;
var a = 2;
var b = 3;
Do<HomeController>(o => o.Save(x, "Jimmy", a+b+5, Math.Sqrt(81)));

public static void Do<T>(Expression<Action<T>> expression) where T : Controller
{
  // get the values 1,Jimmy,10,9 here
}
解决方案

Well, you'd need to drill into the expression, find the MethodCallExpression, and then look at the arguments to it. Note that we don't have the value of o, so we've got to assume that the arguments to the method don't rely on that. Also we're still assuming that the lambda expression just relies on it being a MethodCallExpression?

EDIT: Okay, here's an edited version which evaluates the arguments. However, it assumes you're not really using the lambda expression parameter within the arguments (which is what the new object[1] is about - it's providing a null parameter, effectively).

using System;
using System.Linq.Expressions;

class Foo
{
    public void Save(int x, string y, int z, double d)
    {
    }
}

class Program
{
    static void Main()
    {
        var x = 1;
        var a = 2;
        var b = 3;
        ShowValues<Foo>(o => o.Save(x, "Jimmy", a + b + 5, Math.Sqrt(81)));
    }

    static void ShowValues<T>(Expression<Action<T>> expression)
    {
        var call = expression.Body as MethodCallExpression;
        if (call == null)
        {
            throw new ArgumentException("Not a method call");
        }
        foreach (Expression argument in call.Arguments)
        {
            LambdaExpression lambda = Expression.Lambda(argument,
                                                        expression.Parameters);
            Delegate d = lambda.Compile();
            object value = d.DynamicInvoke(new object[1]);
            Console.WriteLine("Got value: {0}", value);
        }
    }
}

这篇关于从拉姆达EX pressions方法参数得到最终值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!

08-06 09:37