title: How to create an autocomplete list in ViM?
body: <p>As I am typing code, I would like to get the symbol before and after a specific character (e.g. '.' in C#) and pass that to my own program which would then in return give a list of possible completions.</p>
  
  <p>For example if user is typing:</p>
  
  <pre><code>m_Filename.M
  </code></pre>
  
  <p>I would want to call out into my own DLL/EXE passing "m_Filename" and "M" and my program return a list such as</p>
  
  <pre><code>Match
  Matches
  </code></pre>
  
  <p>And have that popup in a list in ViM for autocompletion suggestions.</p>
  
  <p>Note that this is not asking how to write the DLL/EXE which provides the suggestions, just the functionality in ViM for autocomplete .</p>