Maui custom handlers without hash ifs everywhere

I don’t know about you but I really do not like having #if definitions dotted around all over my codebase and I try my best to avoid it where I can. Currently a mechanism to configure new custom handlers within MAUI can require you to make use of the #if statement as seen below:

appBuilder
    .UseMauiApp<App>()
    .ConfigureMauiHandlers(handlers =>
    {
#if __ANDROID__
        handlers.AddHandler(typeof(CustomEntry), typeof(CustomEntryHandler));
#endif
    });

I would like to propose an alternative. There are a few steps:

1. Create a common static partial class to remove the need for #if

namespace MyFirstMauiApplication
{
    public static partial class CustomHandlerRegistrar
    {
        public static void Register(IMauiHandlersCollection handlers) =>
            RegisterHandlers(handlers);

        public static partial RegisterHandlers(IMauiHandlersCollection handlers);
    }
}

2. Implement the required parts in your platform specific code

You will need to create a class in each platform AND make sure that the namespace matches that of the original CustomHandlerRegistrar.

namespace MyFirstMauiApplication
{
    public static partial class CustomHandlerRegistrar
    {
        public static partial RegisterHandlers(IMauiHandlersCollection handlers)
        {
            handlers.AddHandler(typeof(CustomEntry), typeof(CustomEntryHandler));
        }
    }
}

3. Remove the #if from Startup.cs

This then results in a much cleaner looking Startup.cs file.

appBuilder
    .UseMauiApp<App>()
    .ConfigureMauiHandlers(handlers => CustomHandlerRegistrar.Register(handlers));

#maui, #dotnet