C# Cookbook

6.14. Enable/Disable Complex Tracing Code

Problem

You have an object that contains complex tracing/debugging code. In fact, there is so much tracing/debugging code that to turn it all on would create an extremely large amount of output. You want to be able to generate objects at runtime that contain all of the tracing/debugging code, only a specific portion of this tracing/debugging code, or that contain no tracing/debugging code. The amount of tracing code generated could depend on the state of the application or the environment where it is running. The tracing code needs to be generated during object creation.

Solution

Use the TraceFactory class, which implements the Simple Factory design pattern to allow creation of an object that either generates tracing information or does not:

#define TRACE
#define TRACE_INSTANTIATION
#define TRACE_BEHAVIOR

using System.Diagnostics;

public class TraceFactory
{
    public TraceFactory( ) {}

    public Foo CreateObj( )
    {
        Foo obj = null;

        #if (TRACE)
            #if (TRACE_INSTANTIATION)
                obj = new BarTraceInst( );
            #elif (TRACE_BEHAVIOR)
                obj = new BarTraceBehavior( );
            #else
                obj = new Bar( );
            #endif
        #else
            obj = new Bar( );
        #endif

        return (obj);
    }
}

The class hierarchy for the Bar, BarTraceInst, and BarTraceBehavior classes is shown next. The BarTraceInst class would contain only the constructor tracing code, the BarTraceBehavior class contains only tracing code within specific methods, and the Bar class contains no tracing code:

public abstract class Foo { public virtual ...