Thursday, February 16, 2012

Create a fast compiled method invoker using LINQ

  1. var method = new Func<double, double, double>(Math.Pow).Method;
  2. var parameter = Expression.Parameter(typeof(object[]));
  3. var args = method.GetParameters()
  4. .Select((param, i) => Expression.Convert(
  5. Expression.ArrayIndex(parameter, Expression.Constant(i)), param.ParameterType));
  6. var expr = Expression.Lambda<Func<object[], object>>(
  7. Expression.Convert(Expression.Call(method, args), typeof(object)), parameter);
  8. var invoker = expr.Compile();
  9. var result = invoker(new object[] {Math.PI, 2.0});

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