title: static method or non-static method using static field
body: <p>I have a <code>static const std::vector&lt;SomeType&gt;</code> field in my class. I have two <code>private</code> methods that uses this field (searching methods). 
  They do not use another members of my class. Should they be define as <code>static</code> or normal methods?</p>
  
  <p>What should I prefer? What are advantages/disadvantages?</p>