编译需要参数的表达式 [英] Compile expression that requires a parameter

问题描述

好吧，我敢肯定这很简单，但是我有一个重要的时刻.

Ok, I am sure this is simple, but I am having a senior moment.

我有一个简单的BinaryExpression(greaterthan)，左侧是ParameterExpression，右侧是ConstantExpression，我想将此表达式编译为可以调用并将参数传递给...的函子.

I have a simple BinaryExpression (greaterthan) the left side is a ParameterExpression and the right side is a ConstantExpression I want to compile this expression to a func that I can call and pass a parameter to...

var func = ...something with my exp....

bool result = func(myValue);

多亏了哈桑，我修改了他对我的需求的答案...

Thanks to Hasan, I modified his answer to my needs...

var func = Expression.Lambda<Func<int,bool>>(myExpr, (ParameterExpression)myExpr.left).Compile();

推荐答案

var param = Expression.Parameter(typeof(int));
var value = Expression.Constant(3);
var body = Expression.GreaterThan(param, value);
var checkValue = Expression.Lambda<Func<int, bool>>(body, param).Compile();

Console.WriteLine(checkValue(4));
Console.WriteLine(checkValue(2));

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