Here is me longing,for the switch expression in 2011.
Frank Quednau
@flq.freiburg.social.ap.brid.gy
15 followers 0 following 196 posts
Software gardener living in Germany’s South-West. EN, DE, ES. #dotnet #typescript 🌉 bridged from ⁂ freiburg.social/@flq, follow @ap.brid.gy to interact
![A c# helper that can be used on exception types to throw if an assertion is not fulfilled:
public static class ExceptionAssertion
{
private static readonly ConcurrentDictionary<Type, Func<string, Exception>> Factories = new();
extension<T>(T) where T : Exception, new()
{
/// <summary>
/// Throws the exception you call this on when the assertion is false.
/// Note that if that particular exception does not provide a constructor that takes a string,
/// the default constructor will be used.
/// </summary>
public static void ThrowIfFalse([DoesNotReturnIf(false)] bool assertion, string message)
{
if (!assertion)
{
throw Factories.GetOrAdd(typeof(T), CreateFactory)(message);
}
}
}
private static Func<string, Exception> CreateFactory(Type exceptionType)
{
const BindingFlags bindingFlags = BindingFlags.Public | BindingFlags.Instance;
var ctor = exceptionType.GetConstructor(bindingFlags, [typeof(string)]) ??
exceptionType.GetConstructor(bindingFlags, [])!;
var message = Expression.Parameter(typeof(string), "message");
Expression[] arguments = ctor.GetParameters().Length == 1 ? [message] : [];
return Expression.Lambda<Func<string, Exception>>(Expression.New(ctor, arguments), message).Compile();
}
}](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:cbmdrysrvdzuombf2ybwxjn7/bafkreigft2cc35i73trmt47puxs3i4mjgadvx6g4ttat3dwyzfur5q4fy4)
![The code line:
var listLike = (obj.List ?? [])
does not work as there is no target type for the collection expression.](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:cbmdrysrvdzuombf2ybwxjn7/bafkreiftay64fxydxjlhf72m6dm6qmqol5qb7bzexjmnhjzbwe3z4dqo24)
