Question

is it possible to create an anonymous method in c# from a string?

e.g. if I have a string "x + y * z" is it possible to turn this into some sort of method/lambda object that I can call with arbitrary x,y,z parameters?

Answer 1

It’s possible, yes. You have to parse the string and, for example, compile a delegate using expression trees.

Here’s an example of creating (x, y, z) => x + y * z using expression trees:

ParameterExpression parameterX = Expression.Parameter(typeof(int), "x");
ParameterExpression parameterY = Expression.Parameter(typeof(int), "y");
ParameterExpression parameterZ = Expression.Parameter(typeof(int), "z");
Expression multiplyYZ = Expression.Multiply(parameterY, parameterZ);
Expression addXMultiplyYZ = Expression.Add(parameterX, multiplyYZ);
Func<int,int,int,int> f = Expression.Lambda<Func<int, int, int, int>>
(
    addXMultiplyYZ,
    parameterX,
    parameterY,
    parameterZ
).Compile();
Console.WriteLine(f(24, 6, 3)); // prints 42 to the console