在派生类的构造函数的主体中初始化基类成员变量

Question

I have a C++ code which I need to rewrite to C# and looks like this:

class dppServerError: public dppBaseError
{
  public :
    dppServerError(DWORD ActionCode, const TCHAR* Desciption)
#ifdef POSTER_VER
        : dppBaseError(Desciption)
#else
        : dppBaseError(TEXT("Server text response: \"%s\""), Desciption)
#endif
        , m_AC(ActionCode), m_ErrorCode(dppERR_SERVER)
    {
    };

Problem is I am not using #defines in my C# code and instead using public const Enums . Now, how can I duplicate above code in C#? the #ifdefs part ? Can't I normally initialize member variables of base class in the body of the constructor of derived class? (without : syntax). Then I could do (in C#):

   dppServerError(uint ActionCode, string Desciption)
    {
       // Initialize base class member
       if(Globals.ConfigEnum == POSTER_VER)
          dppBaseError  = Desciption; // Can I initialize this base class ivar like this? without : syntax?
       else
         dppBaseError = "Smth else" + Desciption;

        // These are just ivars from This class
        m_AC = ActionCode;
        m_ErrorCode = dppERR_SERVER;

    };

PS. Someone told me this about #defines in C#

"Be aware though: there is no guarantee that the conditional compilation symbol is the same for all projects in your solution. This will hinder reuse of your DLLs by other solutions that want different conditional compilation symbols."

And I decided to move to enums because I didn't really get what this meant. I am a bit new to .NET.

Answer 1

If dppBaseError is a field, you can initialize it as you have shown in your code.

If it's a base class constructor, you could do this:

dppServerError(uint ActionCode, string Desciption)
: base( (Globals.ConfigEnum == POSTER_VER) ? Desciption : "Smth else" + Desciption)
{
    ...

Answer 2

To get the same c++ behaviour in c#, use this:

#if POSTER_VER
     dppBaseError  = Desciption;    
#else
    dppBaseError = "Smth else" + Desciption;
#endif

or also:

dppServerError(uint ActionCode, string Desciption)
#if POSTER_VER
    :base(Desciption)
#else
    :base("Smth else" + Desciption)
#endif 

Use a #define POSTER_VER directive, or better, define the symbol in project properties -> build -> Conditional compilation symbols.

Usually a source file is included only in one project (unless you use "add as link " in visual studio to add same file to two or more projects), so the remarks "be aware" does not apply. if it does, use the same care you would use for c++ code.

In you c# code , the variable Global.ConfigEnum is evaulated at runtime , in my c# code, as in your c++, the symbol POSTER_VER is checked at complile time , resulting in different compiled binary files.

see #if , #define and ProjectProperties on MSDN