Non static class with only static methods

DaveyM69

I have noticed looking at MS source that they regularly do this for a class with only static methods instead of creating a static class:

public class ClassName
{
private ClassName()
{ }

public static void Method()
{
    // ...
}

}

Is there any benifit to this that I'm missing over a static class?

Dave
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musefan

Perhaps so the class can be inherited? just a guess

Don't vote my posts down just because you don't understand them - if you lack the superior intelligence that I possess then simply walk away

PIEBALDconsult

Pre version 2? Backward compatibility?

Bernhard Hiller

COM Interop? COM requires a public constructor without parameters, and there it is. And isn't it possible to access class methods through an instance with COM? When I remember those times when I was VB programmer correctly, that was possible, but I am not sure.

Gregory Gadow

I think this is laziness on the part of MS. If (when?) the class definition changes in the Framework, the documentarians won't have to root around in the code to make sure that every method is still static.

Gregory Gadow

Which sounds plausable, but why allow the class to be instanced (by making it non-static) when it can never be instantiated (because the constructor is private)? Backwards compatibility is going to break anyway, just in a much more awkward spot.

Karthik A

You could use static methods if the functionality of the method is not dependent on the instance properties/methods. Consider the following class as an example. There is a static "Parse" method that takes in a string and return a new instance of "Data". This static function "does not" depend on any of the instance properties/methods of the Data class. But it just creates an instance of the Data class for you to use. So, any other class that wishes to create an instance of Data (which has a ',' seperated int's) can do so by calling Data.Parse(_stringValue).

public class Data
{
private List a;

public Data()
{
  a = new List();
}

public Data(int\[\] nums)
{
   a = new List();
   // add to a
}

public static Data Parse(string nums)
{
   // say nums = "1,2,3
   string\[\] \_nums = nums.Split(",".ToCharArray());
   List iList = new List();
   foreach(string s in nums)
      iList.Add(int32.Parse(s));
   return new Data(iList.ToArray());
}

}

PS - This is a just a trivial example of the usage of static methods in a non-static class. Edit - If there are only static methods in a non-static, it might be useless, but it could also be for futuristic reasons. They could add to this class more instance properties / methods in the future that would use these static methods.

Cheers, Karthik

Karthik A

I don't think your argument is valid. Static methods in non-static classes have their own uses. I have given one such (trivial) example.

Cheers, Karthik

Gregory Gadow

I agree: I use static methods in non-static classes all the time. But the question was about non-static classes with nothing BUT static methods.

Karthik A

Yes, I noticed that later. So I also updated my answer to take that in to account (see EDIT in my answer)...

Cheers, Karthik

PIEBALDconsult

Private, schmivate; I can call a private constructor or anything else -- which is why they introduced static classes in .net 2.

Nitin Singh India

A class with a single private default constructor cannot be inherited. It will always need some way to instantiate the parent...

musefan

Yes well spotted. Thou I am not assuming the op sample code is 100% correct still

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