I have a case where the user is entering strings into the application, and I have to match that string with the values from a given Enum. Normally that is not too difficult of a task, just convert the enum item to a string and compare, but in this instance I have a bunch of enums to do this with, so I didn’t want to write a separate function for each enum type. So I figured generics might provide a solution and here is what I came up with, which is loosely based on the idea of int.TryParse:
/// <SUMMARY> /// Takes a string that represents an enum member /// and returns the enum member /// </SUMMARY> /// <TYPEPARAM name="T">An Enum</TYPEPARAM> /// <PARAM name="input"> /// The string that is the enum member name, case does /// not matter /// </PARAM> /// <PARAM name="returnValue"> /// The value from the enum that matches the string, or the /// first value of the enum /// </PARAM> /// <RETURNS> /// True when there is a match, false when not /// </RETURNS> /// <REMARKS> /// - When no match the first item in the enum is returned /// - The where clause attempts to constrain the input of T
/// at compile time to be an Enum /// </REMARKS> private bool GetEnumValue<T>(string input, out T returnValue)
where T : struct, IComparable, IFormattable, IConvertible { if(Enum.IsDefined(typeof(T), input)) { returnValue = (T)Enum.Parse(typeof(T), input, true); return true; } else //input not found in the Enum, fill the out parameter
// with the first item from the enum { string[] values = Enum.GetNames(typeof(T)); returnValue = (T)Enum.Parse(typeof(T), values[0], true); return false; } }
