.NET Compiler -- DEBUG vs. RELEASE

Question

For years I have been using the DEBUG compiler constant in VB.NET to write messages to the console. I've also been using System.Diagnostics.Debug.Write in similar fashion. It was always my understanding that when RELEASE was used as the build option, that all of these statements were left out by the compiler, freeing your production code of the overhead of debug statements. Recently when working with Silverlight 2 Beta 2, I noticed that Visual Studio actually attached to a RELEASE build that I was running off of a public website and displayed DEBUG statements which I assumed weren't even compiled! Now, my first inclination is to assume that that there is something wrong with my environment, but I also want to ask anyone with deep knowledge on System.Diagnostics.Debug and the DEBUG build option in general what I may be misunderstanding here.

Answer 1

The preferred method is to actually use the conditional attribute to wrap your debug calls, not use the compiler directives. #ifs can get tricky and can lead to weird build problems.

An example of using a conditional attribute is as follows (in C#, but works in VB.NET too):

[ Conditional("Debug") ]
private void WriteDebug(string debugString)
{
  // do stuff
}

When you compile without the DEBUG flag set, any call to WriteDebug will be removed as was assumed was happening with Debug.Write().

Answer 2

Examine the Debug.Write method. It is marked with the

[Conditional("DEBUG")]

attribute.

The MSDN help for ConditionalAttribute states:

Indicates to compilers that a method call or attribute should be ignored unless a specified conditional compilation symbol is defined.

Whether the build configuration has a label of release or debug doesn't matter, what matters is whether the DEBUG symbol is defined in it.