Hi, A recent commit [1] changed, among other things, some string equality comparisons from `SomeComparer.Compare(a, "B", IgnoreCase) == 0` to `a.ToUpperInvariant() == "B"`, see also [2]. Unfortunately, this doesn't work if `a` is allowed to be null. Currently a lot of log4net.Tests are broken because of such a null reference exception in `NewLinePatternConverter.ActivateOptions` (apparently "%newline" is quite common in pattern layouts ;-). For new code I tend to opt for `String.Equals(Option, "DOS", StringComparison.OrdinalIgnoreCase)` for a fast, case-insensitive comparison with fixed ASCII-only patterns, but static `String.Equals(String, String, StringComparison)` is not awailable on .NET-1.x [3].
So - `a.ToUpperInvariant() == "FOO" is not null-save and produces needless intermediate strings on the heap (and culture-aware operations are slower then nesessary for pure ASCII-stuff), - `SomeComparer.Compare(a, "B", IgnoreCase) == 0` is hard to read, esp. when the compater is "long". - we need .NET-1.x support, so all the goodness from [4] does not apply. Should we create some helper in SystemInfo that provides null-aware, ordinal, casing-agnostic string equality comparison, with some #if's .NET-1.x? Who needs .NET-1.x? The current solution with `ToUpperInvariant` is also .NET-2.0... [1]: r1756284 ".NET Core improvements by Peter Jas - closes #30" [2]: https://github.com/apache/log4net/pull/16#discussion_r74683879 [3]: https://msdn.microsoft.com/en-us/library/t4411bks(v=vs.110).aspx#Anchor_4 [4]: https://msdn.microsoft.com/en-us/library/ms973919.aspx Regards, Jonas
