Extension method must be defined in non-generic static class

Question

Error at:

public partial class Form2 : Form 

Probable cause:

public static IChromosome To<T>(this string text) {     return (IChromosome)Convert.ChangeType(text, typeof(T)); } 

Attempted (without static keyword):

public IChromosome To<T>(this string text) {     return (IChromosome)Convert.ChangeType(text, typeof(T)); } 

Answer 1

If you remove "this" from your parameters it should work.

public static IChromosome To<T>(this string text) 

should be:

public static IChromosome To<T>(string text) 

Answer 2

The class containing the extension must be static. Yours are in:

public partial class Form2 : Form 

which is not a static class.

You need to create a class like so:

static class ExtensionHelpers {     public static IChromosome To<T>(this string text)      {          return (IChromosome)Convert.ChangeType(text, typeof(T));      }  } 

To contain the extension methods.