Is it possible to access an instance variable via a static method?

Question

In C#, is it possible to access an instance variable via a static method in different classes without using parameter passing?

In our project, I have a Data access layer class which has a lot of static methods. In these methods the SqlCommand timeout value has been hard-coded. In another class(Dac) in our framework there are many instance methods which call these static methods.

I don't want to code too much using parameter passing. Do you have any other solution which is easier than parameter passing?

A static method is not associated with any instance so how do you expect it to know which instance to access a member of? — Mark Byers
– Mark Byers, Commented Jul 30, 2010 at 13:38

Mark Byers · Accepted Answer · 2010-07-30 13:30:36Z

14

Yes, it is possible to access an instance variable from a static method without using a parameter but only if you can access it via something that is declared static. Example:

public class AnotherClass
{
    public int InstanceVariable = 42;
}

public class Program
{
    static AnotherClass x = new AnotherClass(); // This is static.

    static void Main(string[] args)
    {
        Console.WriteLine(x.InstanceVariable);
    }
}

edited Jul 30, 2010 at 13:30

answered Jul 30, 2010 at 13:25

Mark Byers

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1 Comment

Jeff Sternal Over a year ago

+1, but oh the horror of global variables!

Jake Pearson · Accepted Answer · 2010-07-30 13:25:06Z

7

Sure, you could pass an instance as a parameter to the method. Like:

public static void DoSomething(Button b)
{
    b.Text = "foo";
}

But it wouldn't be possible to get at any instance variables otherwise.

answered Jul 30, 2010 at 13:25

Jake Pearson

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Comments

Justin Niessner · Accepted Answer · 2010-07-30 14:03:49Z

6

A static method has no instance to work with, so no. It's not possible without parameter passing.

Another option for you might be to use a static instance of the class (Mark's example shows this method at work) although, from your example, I'm not sure that would solve your problem.

Personally, I think parameter passing is going to be the best option. I'm still not sure why you want to shy away from it.

edited Jul 30, 2010 at 14:03

answered Jul 30, 2010 at 13:25

Justin Niessner

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1 Comment

siride Over a year ago

The edit boils down to "I don't want to", which is not a good technical reason. The alternative is really really bad, if not impossible.

Richard Friend · Accepted Answer · 2010-07-30 13:45:15Z

2

Yes it can, as long as it has an instance of an object in scope. Singletons for instance, or objects created within the method itself..

Take for example a common scenario :

public static string UserName
{
   return System.Web.HttpContext.Current.User.Identity.Name;
}

answered Jul 30, 2010 at 13:45

Richard Friend

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Comments

Brian R. Bondy · Accepted Answer · 2010-07-30 13:30:13Z

1

No you can't.

If you want to access an instance variable then your method by definition should not be static.

answered Jul 30, 2010 at 13:30

Brian R. Bondy

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2 Comments

Richard Friend Over a year ago

What about accessing instance properties of singletons ?

Brian R. Bondy Over a year ago

@Richard: With a singleton you have an instance, and the methods would not be static in that case. Only the method to get the singleton instance is static.

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