Difference between 'enumType' and 'TEnum'

Question

Guy new to C# here. I was looking around MSDN skimming through enum methods, but I could not tell the difference between TEnum and enumType.

public static bool TryParse<TEnum>(
string value,
out TEnum result)

public static string[] GetNames(
Type enumType)

What is the difference here? For the first method, wouldn't it possibly be better to return enumType result instead?

Answer 1

TEnum is the Generic type of enumeration. You can pass any of your enumeration to that method.

The second method is a non-generic one, where you would use a typeof keyword to identify the enums and return the enum names as a string collection

Answer 2

In TryParse<TEnum>() is a generic method and TEnum is the generic type parameter. Any time you see a method, class, or interface declaration followed by a name in angle brackets you have a generic type. Generics are used to provide compile time type checks and improve performance by specifying the type the method is to use.

GetNames takes a Type object. A particular Type object represents particular class, interface, or enum. It's probably better to compare to Enum.Parse:

public static Object Parse(
    Type enumType,
    string value
);

Notice that Enum.Parse returns an object, which will require a cast to TEnum.

Generics where not added until .Net 2.0 so you will see a number of methods that have a generic version and a generic version that takes a Type object. The non-generic versions are also useful when working with reflection.