S2223_c#.html

<p>Non-private <code>static</code> fields that are neither <code>const</code> nor <code>readonly</code> can lead to errors and unpredictable
behavior.</p>
<p>This can happen because: * Any object can modify these fields and alter the global state. This makes the code more difficult to read, debug and
test. * Correctly accessing these fields from different threads needs synchronization with <code>lock</code>. Improper synchronization may lead to
unexpected results.</p>
<p>Publicly visible static fields should only be used to store shared data that does not change. To enforce this intent, these fields should be marked
<code>readonly</code> or converted to <code>const</code>.</p>
<h2>Noncompliant Code Example</h2>
<pre>
public class Math
{
  public static double Pi = 3.14;  // Noncompliant
}
</pre>
<p>or</p>
<pre>
public class Shape
{
  public static Shape Empty = new EmptyShape();  // Noncompliant

  private class EmptyShape : Shape
  {
  }
}
</pre>
<h2>Compliant Solution</h2>
<pre>
public class Math
{
  public const double Pi = 3.14;
}
</pre>
<p>or</p>
<pre>
public class Shape
{
  public static readonly Shape Empty = new EmptyShape();

  private class EmptyShape : Shape
  {
  }
}
</pre>