The number of arguments given for the lambda declaration is incorrect.

.net c# expression-trees lambda

Question

Please glance through my code: I'm attempting to makemyCar the use of an Expression Tree.

I obtain aArgumentException to the leftvar m = Expression.Lambda<Func<Engine,... The text is 18-zzz-zz.

public class Engine
{
    public string Name { get; private set; }
    public Engine(string name)
    {
        Name = name;
    }
}
public class Car
{
    private readonly Engine engine;
    public Car(Engine engine)
    {
        this.engine = engine;
    }
    public string GetEngineName(){return engine.Name;}
}
class Program
{
    static void Main(string[] args)
    {
        var ci = typeof (Car).GetConstructor(new[] {typeof (Engine)});

        var engine = Expression.Parameter(typeof (Engine));

        var m = Expression.Lambda<Func<Engine,Car>>(Expression.New(ci, engine))
                          .Compile();

        var myCar = m(new Engine("TDI 2.0"));
        var s = myCar.GetEngineName();
    }
}

I'm unable to identify the problem or the location of my mistake. I appreciate it.

1
6
4/23/2013 3:32:19 PM

Accepted Answer

The engine must be specified in the Expression's "params ParameterExpression[] parameters" section. Lambda

var m = Expression.Lambda<Func<Engine, Car>>(Expression.New(ci, engine), engine)
13
1/21/2011 12:38:55 PM


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