DarkSaner's blog

From the foundations of my software programming skills, there is c++. Even if I used to develop with Java and now mainly use c# in a professional way and Objective-C and c++/Qt as hobbies.

A few days ago, I was in totally confusion about a type of use of the new keyword in c#.

New in c# has two different kinds of use : operator and modifier.

operator use

In C++, the new keyword instantiates objects on the heap. There are some differences in C# : With reference types, a new statement instantiates objects on the heap, but with value types such as structs or simple types, objects are created on the stack and a constructor is called.
if you don’t use new keyword with value type, the object is created on the stack, too. But be careful! New initializes objects. If you don’t use new, you must initialize all the values in the struct or simple type by hand before you use it or it won’t compile. (ref. microsoft).

Another difference between c++ and c# is : the new operator can’t be overloaded in c#.

So, in the operator use, there are some differences between c++ and c#, but all in all it’s the same.

modifier use

My confusion is about using new in c# in a modifier way… New keyword is used to explicitly hide an inherited member…And this use case is very confusing if you come from the c++…and even if not ! See below :

In order to “hide” an inherited member of a class, you can declare it in the derived class using the same name, and “modify” it with the new modifier…

class ABase
{
   public void DoJob() {}
}
class A: ABase
{
   new public void DoJob() {}
}

So, a call to A.DoJob(); will call the A method in all use cases…But honestly, what is the utility of this ?!

One more thing, the code will exactly work the same way without the new. The only difference is a warning like this :

“The keyword new is required on ‘A.DoJob’ because it hides inherited method ‘ABase.DoJob’.”

In my opinion, using new keyword in a modifier way is to be avoided absolutly ! Use “polymorphic compliant” code and “multi languages comprehensible” code using virtual and override keywords instead !

class ABase
{
   public virtual void DoJob() {}
}
class A: ABase
{
   public override void DoJob() {}
}

A lot of programmers will tell you…Thanks ! Starting by me…

Converting a string to an enum item wasn’t very obvious (actually for me )… But it’s quite easy after found the right method…Let’s see below :

enum FilmMakingSteps
{
      Development,
      PreProduction,
      Production,
      PostProduction,
      SalesAndDistribution,
} ;

FilmMakingSteps filmMakingStep = (FilmMakingSteps) Enum.Parse(typeof(FilmMakingSteps), "Production");
// filmMakingStep is the Production item !
// Problem, picking an invalid string throws an ArgumentException.
// So, call first Enum.IsDefined(), as follows:
string noneFilmMakingStep = "Photography";
if (Enum.IsDefined(typeof(FilmMakingSteps), noneFilmMakingStep))                                                                                                                                                                 
      filmMakingSetp = (FilmMakingSteps) Enum.Parse(typeof(FilmMakingSteps), noneFilmMakingStep, false);// false = case-sensitive
else
      MessageBox.Show("Not a valid filmmaking step !"); // is called !