Improve handling of Exception<T>

[elachlan]

Fixes #83.

Reference: https://stackoverflow.com/questions/17480990/get-name-of-generic-class-without-tilde

[niemyjski]

Thanks for the PR, can we also add test cases specifically addressed in the issue around structs. I also left some feedback about performance concerns

@ejsmith should we be worried about this creating lots of new stacks due to hash changes for type names?

[elachlan]

How about this?

private static readonly ConcurrentDictionary<Type, string> TypeNameCache = new ConcurrentDictionary<Type, string>();
public static string GetRealTypeName(this Type t) {
    if (TypeNameCache.TryGetValue(t, out string name)) {
        return name;
    }
    if (!t.IsGenericType)
        return t.FullName.Replace('+','.');

    StringBuilder sb = new StringBuilder();
    ReadOnlySpan<char> fullName = t.FullName.AsSpan();
    int plusIndex = fullName.IndexOf('+');
    if (plusIndex > 0) {
        sb.Append(fullName.Slice(0, plusIndex).ToArray());
        sb.Append('.');
    }
    int length = fullName.IndexOf('`') - (plusIndex > 0 ? plusIndex + 1 : 0);
    sb.Append(fullName.Slice(plusIndex > 0 ? plusIndex + 1 : 0, length).ToArray());
    sb.Append('<');
    bool appendComma = false;
    foreach (Type arg in t.GetGenericArguments()) {
        if (appendComma) { sb.Append(','); }
        sb.Append(GetRealTypeName(arg));
        appendComma = true;
    }
    sb.Append('>');
    return TypeNameCache.GetOrAdd(t, sb.ToString());
}

[elachlan]

Should I just use the TypeNameHelper?

Exceptionless.Net/src/Exceptionless/Demystifier/TypeNameHelper.cs

Lines 48 to 53 in 118b006

	public static string GetTypeDisplayName(Type type, bool fullName = true, bool includeGenericParameterNames = false)
	{
	var builder = new StringBuilder();
	ProcessType(builder, type, new DisplayNameOptions(fullName, includeGenericParameterNames));
	return builder.ToString();
	}

Only issue I see is that it includes the +, so instead of:
Exceptionless.Tests.Plugins.PluginTestBase.GenericException<Exceptionless.Tests.Plugins.PluginTestBase.ErrorCategory>
You get:
Exceptionless.Tests.Plugins.PluginTestBase+GenericException<Exceptionless.Tests.Plugins.PluginTestBase+ErrorCategory>

If this is okay, I will use that. I also suggest we add a cache of some kind to TypeNameHelper.

[elachlan]

@niemyjski How is that? Do you want a couple more test cases?

[elachlan]

@ejsmith any chance of a quick review?

[niemyjski]

Left some comments, It's nice that we found an existing method that handles this!

[elachlan]

Left some comments, It's nice that we found an existing method that handles this!

All sorted. Thanks for the review!

[niemyjski]

Looks good

[niemyjski]

Thanks for the PR! These are really nice changes @elachlan was there any other changes you wanted to get in prior to a release?

[elachlan]

Thanks for the PR! These are really nice changes @elachlan was there any other changes you wanted to get in prior to a release?

I won't have the time to work on this for the next two weeks.

I was going to look at using spans in place of string operations at some point.

[niemyjski]

I think if anything, we just report this possible optimization to the upstream dependency.

[elachlan]

Is this the upstream?
https://github.com/benaadams/Ben.Demystifier/

[niemyjski]

Yes