C#产品代码, 将int cast为一个enum类型永远不会抛出异常

这是语言标准所保证的, 在产品代码中看到:

try

{

     someEnumVariable = (TheEnumType) (int_variable_in_parameter_comes_from_caller);

}

catch(Exception ex)

{

     Log.Error(" invalid typpe " +int_variable_in_parameter_comes_from_caller);

}

 

这样的catch永远不会发生, 若需要检测未定义的enum值, 可以用 Enum.IsDefined, 但要注意这个方法会抛出 ArgumentException异常:

public enum X : byte

{

   a = 0

}

 

int x = 0;

Enum.IsDefined( typeof(TheEnumType), x );

错误信息是:

System.ArgumentException: Enum underlying type and the object must be same type or object must be a String. Type passed
in was 'System.Int32'; the enum underlying type was 'System.Byte'.

 

正确的做法是:

TheEnumType e = (TheEnumType) x;

if ( Enum.IsDefined( typeof(TheEnumType), e) == false)

{  ... }