Question

I need to pass the lambda query as a parameter, the followings code is sample and I am interesting to find an implement for it, there is samples: some thing like this:

var expr1 = Where(n => n > 6).OrderBy(n => n % 2 == 0).Select(n => n);
var expr2 = TakeWhile((n, index) => n >= index));

And Use it Like this:

public void UseLambda<T> (IEnumerable<T> source , lambda Expr){

var items= Expr.Compile(source);

foreach(var item in items)
     Console.Writeline(item.ToString());
}

public void Main(){
    List<int> numbers = new List<int> { 10, 24, 9, 87, 193, 12, 7, 2, -45, -2, 9 };
    var expr1 = Where(n => n > 6).OrderBy(n => n % 2 == 0).Select(n => n);
    UseLambda(numbers, expr1);
}

Does any one have an idea about it?

Answer 1

If you define your LINQ expressions like this:

Func<IEnumerable<int>, IEnumerable<int>> expr1 =
               l => l.Where(n => n > 6).OrderBy(n => n % 2 == 0).Select(n => n);

Func<IEnumerable<int>, IEnumerable<int>> expr2 = 
               l => l.TakeWhile((n, index) => n >= index);

And your UseLambda method as:

public void UseLambda<T> (IEnumerable<T> source 
                          ,Func<IEnumerable<T>, IEnumerable<T>> lambda)
{
    var items= lambda(source);

    foreach(var item in items)
       Console.Writeline(item.ToString());
    }
}

Then you I think you have what you’re looking for.