What is chain.doFilter doing in Filter.doFilter method?

Question

In a Filter.doFilter method I made this call chain.doFilter.

What is doFilter doing inside a doFilter? Isn\'t it a recursive call?

Answer 1

Not having any code that you are talking about, I can only assume that you something like:

class Filter implements FilterAPI {
  private FilterAPI chain;
  FilterAPI(FilterAPI chain) { this.chain = chain; }
  @override void doFilter (Set setToFilter) {
    // do some filtering on setToFilter
    chain.doFilter(setToFilter);
  }
}

If that is the case, then you are not calling anything recursively, you are calling doFilter() on a different object. As mentioned on an another answer, this is the well known Chain of Responsibility design pattern.