C# generic method with integer constraint refuses to cast from integer to the generic type
c#, generics
Solution
"Only class or interface could be specified as constraint." (c) ReSharper
int (Int32) is just a struct. You can constrain that T is a struct. but you can't use any struct as constraint.
the whole list of possible constraints you can find here - http://msdn.microsoft.com/en-us/library/d5x73970.aspx
UPD
and for Enum constraint see this question - Is there a workaround for generic type constraint of "special class" Enum in C# 3.0?
Problem
If I have a generic method that is constrained to be type 'int' then surely I should be able to cast an integer to the generic T type. For example... ``` public T ExampleMethod<T>(int unchanged) where T : int { return (T)unchanged; } ``` ...the compiler complains that Cannot convert type 'int' to 'T' but I have a constraint indicating that the target is as integer. So surely it should work? Update: The actual scenario is that I want to a helper method that returns an enum value. So my ideal helper method would be more like this.... ``` public T GetAttributeAsEnum<T>(XmlReader reader, string name) where T : enum { string s = reader.GetAttribute(name); int i = int.Parse(s); return (T)i; } ``` ...and use it like this... ``` StateEnum x = GetAttributeAsEnum<StateEnum>(xmlReader, "State"); CategoryEnum y = GetAttributeAsEnum<CategoryEnum>(xmlReader, "Category"); OtherEnum z = GetAttributeAsEnum<OtherEnum>(xmlReader, "Other"); ``` ...but you cannot constrain by enum.