Add verbose warn and error log methods to node

[mamaso]

resolves #304

[mathewc]

I'm finding the following code very difficult to understand/read. Maybe its just me, but its making my head hurt

[mamaso]

fair, a more C# style is probably better for maintainability

basic idea was 'log' is an object of tracewriter methods. We need to decorate those methods with the util.format code and then get it into a format where context.log is the info tracewriter with all the tracewriter methods attached to it as properties (C# doesn't seems to have the idea of callable objects (I guess it would be extending Func?), which is what this is mapping to)

[mathewc]

I was thinking that you could construct the set of log methods in this code, but have them all funnel down into a single log call into the func exposed from .NET - just passing in an object of the form { level: 'info', message: '...' }. That allows us to just have a single simple method in .NET receiving all of these. For example:

var origLog = context.log;
var logLevel = function (level) {
    return function () {
        var message = util.format.apply(null, args);
        origLog({ level: level, message: message});
    };
}
var levels = ['info', 'verbose', 'warn', 'error' ];
var log = logLevel('info');
levels.foreach(level => {
    log[level] = logLevel(level);
});
context.log = log;

[mathewc]

I was thinking this would all be much simpler if we just make the existing log be a function that takes and object like { level: 'info', message: '...' }. Our node adapter code then passes in such objects, and we map like:

// create a TraceWriter wrapper that can be exposed to Node.js
var log = (Func<object, Task<object>>)(p =>
{
    var logData = (IDictionary<string, object>)p;
    string message = (string)logData["message"];
    if (message != null)
    {
        try
        {
            TraceLevel level = (TraceLevel)Enum.Parse(typeof(TraceLevel), (string)logData["level"]);
            var evt = new TraceEvent(level, message);
            traceWriter.Trace(evt);
        }
        catch (ObjectDisposedException)
        {
            // if a function attempts to write to a disposed
            // TraceWriter. Might happen if a function tries to
            // log after calling done()
        }
    }

    return Task.FromResult<object>(null);
});

[mathewc]

copy paste error? Anyhow, I think you should just add your new cases to the existing logging scenario script and test. simpler that way?

[mathewc]

with my suggestion above, this change shouldn't be needed, right? since log remains a function

[mamaso]

right