Question

GetCached(BLCustomer.GetAll, "GetAll");

where "GetAll" is session key.
How can I do something like this?

GetCached(BLCustomer.GetAll, BLCustomer.GetAll.ToString());

UPDATE:

other worlds I wanna to get the string "GetAll" (not names of customers, but the name of the method) from method name BLCustomer.GetAll().

I want to use something like this

GetCached(BLCustomer.GetSingle, BLCustomer.GetSingle.ToString());

instead of

GetCached(BLCustomer.GetSingle, "GetSingle");

to avoid hardcoding name of methods.

Answer 1

SIMPLE SOLUTION: (stolen from leppie below)

Simply remove the second parameter from your GetCached method:

ReturnType GetCached(Func<T> func)
{
    var name = func.Method.Name;

    // execute func here
}

This assumes, that it will be called like this:

GetCached(BLCustomer.GetAll);

and not like this:

GetCached(() => BLCustomer.GetAll());

---

COMPLEX SOLUTION:

You can do it like this:

string GetMethodName(Expression<Func<Func<dynamic>>> methodExpression)
{
    dynamic memberExpression = methodExpression.Body;
    MethodInfo result = memberExpression.Operand.Arguments[2].Value;
    return result.Name;
}

Call it like this:

GetCached(BLCustomer.GetSingle, GetMethodName(() => BLCustomer.GetSingle));

This approach makes two assumptions:

1. The call always needs to look like in the example, i.e. it mustn’t have a parameter and the body of the delegate must contain only the method you want the name from and nothing else
2. The method you want the name from must not be of type void and must not have any parameters.

You can use this also for non static methods:

BLCustomer customer = new BLCustomer();
GetCached(customer.GetSingle, GetMethodName(() => customer.GetSingle));

You can even change GetCached to the following to cleanup its API:

ReturnType GetCached<T>(Expression<Func<Func<T>>> methodExpression)
{
    var name = GetMethodName(methodExpression);
    var func = methodExpression.Compile()();

    // execute func and do stuff
}

For this to work, you need to make GetMethodName generic instead of using dynamic:

string GetMethodName<T>(Expression<Func<Func<T>>> methodExpression)
{
    dynamic memberExpression = methodExpression.Body;
    MethodInfo result = memberExpression.Operand.Arguments[2].Value;
    return result.Name;
}

And then you can call it like this:

GetCached<IEnumerable<Customer>>(() => BLCustomer.GetAll)
GetCached<Customer>(() => BLCustomer.GetSingle)