Using Func Delegate to set DateTime fields of the class-CodePudding

I have a class with two DateTime fields, I want to have one shared method to set both of them. Would it be possible somehow to do so with Func Delegate?

    private void SetDateTimeField(MyClass class, Func<SupportTicket, DateTime> selector, DateTime date)
    {
      //using selector to select a field of the class and set date parameter to it
    }

and then use it like:

SetDateTimeField(class, c => c.DateTimeField1, DateTime.UtcNow);
SetDateTimeField(class, c => c.DateTimeField2, DateTime.UtcNow);

This question less about practicality of it, but rather understanding how to do it. Is it possible?

CodePudding user response：

If DateTime fields are actually fields (not properties), you can use ref.

var c = new MyClass();

MyClass.SetDateTimeField(c, c => ref c.dt1, DateTime.Now);
MyClass.SetDateTimeField(c, c => ref c.dt2, DateTime.Now);

public class MyClass {
    public DateTime dt1;
    public DateTime dt2;
    
    public delegate ref DateTime Selector(MyClass c);
    
    public static void SetDateTimeField(MyClass c, Selector sel, DateTime dt) {
        sel(c) = dt;
    }
}

CodePudding user response：

Instead of passing a function, pass a function expression. You can then derive the property from the expression and set its value.

public class SupportTicket
{
    public DateTime DT1 { get; set; }
    public DateTime DT2 { get; set; }
}


private static void SetDateTimeField<TObj, TProp>(TObj obj, Expression<Func<TObj, TProp>> selectorExpr, TProp date)
{
    // Get the body of the function as a member access expression
    MemberExpression memberExpr = selectorExpr.Body as MemberExpression;
    if (memberExpr != null)
    {
        // Get the property from the member access expression and set the value
        MemberInfo memberInfo = memberExpr.Member;
        PropertyInfo propertyInfo = memberInfo.DeclaringType.GetProperty(memberInfo.Name);
        propertyInfo.SetValue(obj, date);
    }
    else
    {
        throw new Exception("You must use a member access expression");
    }
}

Sample usage:

SupportTicket ticket = new SupportTicket();
DateTime dt = DateTime.Now;
SetDateTimeField(ticket, e => e.DT1, dt);
SetDateTimeField(ticket, e => e.DT2, dt);

Console.WriteLine(ticket.DT1);
Console.WriteLine(ticket.DT2);
Console.ReadLine();

CodePudding user response：

If you want to change a property based on name you can do it like this:

private void SetDateTimeField(MyClass classX, String selector, DateTime dateX)
{
  //using selector to select a field of the class and set date parameter to it
  var prop = typeof(MyClass).GetProperty(selector);

  prop.SetValue(classX, dateX);


}

SetDateTimeField(class, "DateTimeField1", DateTime.UtcNow);
SetDateTimeField(class, "DateTimeField2", DateTime.UtcNow);