I'm building a function to extend the Enum.Parse concept that
- Allows a default value to be parsed in case that an Enum value is not found
- Is case insensitive
So I wrote the following:
public static T GetEnumFromString<T>(string value, T defaultValue) where T : Enum
{
if (string.IsNullOrEmpty(value)) return defaultValue;
foreach (T item in Enum.GetValues(typeof(T)))
{
if (item.ToString().ToLower().Equals(value.Trim().ToLower())) return item;
}
return defaultValue;
}
I am getting a Error Constraint cannot be special class System.Enum.
Fair enough, but is there a workaround to allow a Generic Enum, or am I going to have to mimic the Parse function and pass a type as an attribute, which forces the ugly boxing requirement to your code.
EDIT All suggestions below have been greatly appreciated, thanks.
Edit 1
HaveI have settled on (I've left the loop to maintain case insensitivity - I am using this when parsing XML)
public static class EnumUtils
{
public static T ParseEnum<T>(string value, T defaultValue) where T : struct, IConvertible
{
if (!typeof(T).IsEnum) throw new ArgumentException("T must be an enumerated type");
if (string.IsNullOrEmpty(value)) return defaultValue;
foreach (T item in Enum.GetValues(typeof(T)))
{
if (item.ToString().ToLower().Equals(value.Trim().ToLower())) return item;
}
return defaultValue;
}
}
EDITEdit 2: (16th Feb 2015) Christopher Currens has posted a compiler enforced type-safe generic solution in MSIL or F# below, which is well worth a look, and an upvote. I will remove this edit if the solution bubbles further up the page.
EDIT 2Edit 3: (13th Apr 2021) As this has now been addressed, and supported, since C# 7.3, I have changed the accepted answer, though full perusal of the top answers is worth it for academic, and historical, interest :)
