if DEBUG vs Conditional DEBUG

Question

Which is better to use  and why  on a large project    if DEBUG     public void SetPrivateValue int value               endif   or   System Diagnostics Conditional  DEBUG    public void SetPrivateValue int value

User · Answer

I have a SOAP WebService extension to log network traffic using a custom  TraceExtension   I use this only for Debug builds and omit from Release builds  Use the  if DEBUG to wrap the  TraceExtension  attribute thus removing it from Release builds    if DEBUG  TraceExtension   endif  System Web Service Protocols SoapDocumentMethodAttribute           more attributes      public DatabaseResponse   GetDatabaseResponse              object   results   this Invoke  GetDatabaseResponse  new object                   parmeters        if DEBUG  TraceExtension   endif public System IAsyncResult BeginGetDatabaseResponse        if DEBUG  TraceExtension   endif public DatabaseResponse   EndGetDatabaseResponse

User · Answer

With the first example  SetPrivateValue won t exist in the build if DEBUG is not defined  with the second example  calls to SetPrivateValue won t exist in the build if DEBUG is not defined   With the first example  you ll have to wrap any calls to SetPrivateValue with  if DEBUG as well   With the second example  the calls to SetPrivateValue will be omitted  but be aware that SetPrivateValue itself will still be compiled   This is useful if you re building a library  so an application referencing your library can still use your function  if the condition is met    If you want to omit the calls and save the space of the callee  you could use a combination of the two techniques    System Diagnostics Conditional  DEBUG    public void SetPrivateValue int value        if DEBUG        method body here      endif

User · Answer

Well  it s worth noting that they don t mean the same thing at all   If the DEBUG symbol isn t defined  then in the first case the SetPrivateValue itself won t be called    whereas in the second case it will exist  but any callers who are compiled without the DEBUG symbol will have those calls omitted   If the code and all its callers are in the same assembly this difference is less important - but it means that in the first case you also need to have  if DEBUG around the calling code as well   Personally I d recommend the second approach - but you do need to keep the difference between them clear in your head

User · Answer

This one can be useful as well   if  Debugger IsAttached

User · Answer

Usually you would need it in Program cs where you want to decide to run either Debug on Non-Debug code and that too mostly in Windows Services  So I created a readonly field IsDebugMode and set its value in static constructor as shown below   static class Program         region Private variable     static readonly bool IsDebugMode   false       endregion Private variable       region Constrcutors     static Program           if DEBUG         IsDebugMode   true    endif            endregion       region Main           lt summary gt          The main entry point for the application           lt  summary gt      static void Main string   args                 if  IsDebugMode                        MyService myService   new MyService args               myService OnDebug                                   else                       ServiceBase   services   new ServiceBase     new MyService  args                 services Run args                         endregion Main

User · Answer

Let s presume your code also had an  else statement which defined a null stub function  addressing one of Jon Skeet s points  There s a second important distinction between the two   Suppose the  if DEBUG or Conditional function exists in a DLL which is referenced by your main project executable  Using the  if  the evaluation of the conditional will be performed with regard to the library s compilation settings  Using the Conditional attribute  the evaluation of the conditional will be performed with regard to the compilation settings of the invoker

User · Answer

I m sure plenty will disagree with me  but having spent time as a build guy constantly hearing  But it works on my machine    I take the standpoint that you should pretty much never use either  If you really need something for testing and debugging  figure out a way to make that testability seperate from the actual production code   Abstract the scenarios with mocking in unit tests  make one off versions of things for one off scenarios you want to test  but don t put tests for debug into the code for binaries which you test and write for production release  These debug tests just hide possible bugs from devs so they aren t found until later in the process

User · Answer

It really depends on what you re going for     if DEBUG  The code in here won t even reach the IL on release   Conditional  DEBUG     This code will reach the IL  however calls to the method will be omitted unless DEBUG is set when the caller is compiled    Personally I use both depending on the situation   Conditional  DEBUG   Example  I use this so that I don t have to go back and edit my code later during release  but during debugging I want to be sure I didn t make any typos  This function checks that I type a property name correctly when trying to use it in my INotifyPropertyChanged stuff    Conditional  DEBUG     DebuggerStepThrough  protected void VerifyPropertyName String propertyName        if  TypeDescriptor GetProperties this  propertyName     null          Debug Fail String Format  Invalid property name  Type   0   Name   1                GetType    propertyName        You really don t want to create a function using  if DEBUG unless you are willing to wrap every call to that function with the same  if DEBUG    if DEBUG     public void DoSomething        endif      public void Foo          if DEBUG         DoSomething      This works  but looks FUGLY  endif         versus    Conditional  DEBUG    public void DoSomething        public void Foo         DoSomething      Code compiles and is cleaner  DoSomething always                      exists  however this is only called during DEBUG         if DEBUG example  I use this when trying to setup different bindings for WCF communication    if DEBUG         public const String ENDPOINT    Localhost    else         public const String ENDPOINT    BasicHttpBinding    endif   In the first example  the code all exists  but is just ignored unless DEBUG is on  In the second example  the const ENDPOINT is set to  Localhost  or  BasicHttpBinding  depending on if DEBUG is set or not     Update  I am updating this answer to clarify an important and tricky point  If you choose to use the ConditionalAttribute  keep in mind that calls are omitted during compilation  and not runtime  That is   MyLibrary dll   Conditional  DEBUG    public void A         Console WriteLine  A        B        Conditional  DEBUG    public void B         Console WriteLine  B        When the library is compiled against release mode  i e  no DEBUG symbol   it will forever have the call to B   from within A   omitted  even if a call to A   is included because DEBUG is defined in the calling assembly

[c#] #if DEBUG vs. Conditional("DEBUG")

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