MVVMCross dynamically construct generic IMvxLog<T> for dependency injection

Question

I'm trying to get Mvx to work in the same way that Microsoft Logging works e.g. ILogger<T> via injection but getting stuck.

I've extended the interface:

public interface IMvxLog<T> : IMvxLog {

}

In my LoginViewModel I want to inject this:

public LoginViewModel(IMvxLog<LoginViewModel> loggger) { }

And then I figured I could dynamically construct by using the below in App.cs:

var logProvider = Mvx.IoCProvider.Resolve<IMvxLogProvider>();
Mvx.IoCProvider.LazyConstructAndRegisterSingleton(typeof(IMvxLog<>), () => logProvider.GetLogFor<>());

It doesn't work as I don't have a type argument to pass to the delegation.

Using the generic method group 'GetLogFor' requires 1 type arguments

How can this be done?

Answer 1

What you're doing there is not allowed, the way Mvx can register these kind of injections is by using open generics typeof(IFoo<>).

You can do what you want by just wrapping the provider GetLogFor in the MvxLog<T> implementation and calls the same methods inside:

public interface IMvxLog<T> : IMvxLog
{
}

public class MvxLog<T> : IMvxLog<T>
{
    private readonly IMvxLog _logImplementation;

    public MvxLog(IMvxLogProvider provider)
    {
        _logImplementation = provider.GetLogFor<T>();
    }

    public bool IsLogLevelEnabled(MvxLogLevel logLevel)
    {
        return _logImplementation.IsLogLevelEnabled(logLevel);
    }

    public bool Log(MvxLogLevel logLevel, Func<string> messageFunc, Exception exception = null, params object[] formatParameters)
    {
        return _logImplementation.Log(logLevel, messageFunc, exception, formatParameters);
    }
}

and then you just register it:

Mvx.IoCProvider.RegisterType(typeof(IMvxLog<>), typeof(MvxLog<>));

and use it like:

public LoginViewModel(IMvxLog<LoginViewModel> loggger) 
{ 
    _logger = logger;    
}

HIH