Question

我需要编译一个lambda表达式，传递一个生成运行时的对象。这是我到目前为止的代码。

一个例子：

var anonType = new { Name = "Florida" }.GetType();
var myObj = Activator.CreateInstance(anonType, "Florida");

var expression = Expression.Parameter(myObj.GetType(), "Name");
var property = Expression.Property(expression, "Name");

var rule = new Rule("Name", "NotEqual", "Florida");

ExpressionType tBinary;

if (!Enum.TryParse(rule.Operator, out tBinary)) return;
var propertyType = myObj.GetType().GetProperty(rule.MemberName).PropertyType;
var right = Expression.Constant(Convert.ChangeType(rule.TargetValue, propertyType));
var result = Expression.MakeBinary(tBinary, property, right);

var expr = Expression.Lambda<Func<Type, bool>>(result, expression).Compile();
var isValid = expr(anonType);

我在尝试编译Lambda表达式时遇到错误。

Additional information: ParameterExpression of type '<>f__AnonymousType0`1[System.String]' cannot be used for delegate parameter of type 'System.Type'

Answer 1

不确定您想要实现的目标，但会回答您的直接问题。您可以在这种情况下编译lambda：

// create Func<AnonymousType, bool>
var func = typeof(Func<,>).MakeGenericType(anonType,typeof(bool));            
// compile
var expr = Expression.Lambda(func, result, expression).Compile();
// invoke
var isValid = expr.DynamicInvoke(new { Name = "NotFlorida" });

有没有办法编译lambda表达式传递对象生成的运行时间？

1 个答案: