只知道名称就抛出异常？

Question

If I have a C# List<string> of exception names (eg. InternalServerErrorException, ConflictException, etc), how would I go about instantiating and throwing the specific exception with nothing more than the string value?

To clarify, I have a simple name as a string pulled from another source, eg. "ConflictException". I need to be able to throw that specific exception.

string myException = "ConflictException";

I cannot just do a throw new myException without first casting (or otherwise converting) to an actual Exception() type. I have tried to do a safe cast, but it cannot convert string to Exception.

Thanks for any ideas.

Answer 1

The short answer is: you can't.

You can't because:

• Exceptions in your list might not be loaded in your current app domain, which could make them impossible to load
• Exceptions don't have a consistent constructor signature, making it error prone to create them using reflection. Although most exception types contain a ctor(string) , not all of them do.

You can try something like this, but keep in mind that it is error prone:

// Load all exceptions once and map their name to their type
var exceptions = (
    from assembly in AppDomain.CurrentDomain.GetAssemblies()
    from type in assembly.GetTypes()
    where type.IsSubclassOf(typeof(Exception))
    where !type.IsAbstract && !type.IsGenericTypeDefinition
    group type by type.Name into g
    select g)
    .ToDictionary(p => p.Key, p => p.First());

// Later on, load a type by its name
string myException = "ConflictException";

Type exceptionType = exceptions[myException];

// Create a new instance, assuming it has a ctor(string)
Exception exception = (Exception)Activator.CreateInstance(
    exceptionType, new object[] { "Some message" });

// throw the exception
throw exception;