title: What's the C# equivalent of perl warn?
body: <p>In Perl I can say</p>
  
  <pre><code>use warnings;
  warn "Non-fatal error condition, printed to stderr.";
  </code></pre>
  
  <p>What is the equivalent of this in C# ASP.NET? Specifically what I'm looking for is something so that other members of my team can know when they're still using a deprecated routine. It should show up at run time when the code path is actually hit, not at compile time (otherwise they'd get warnings about code sitting at a compatibility layer which ought to never run anyway.)</p>
  
  <p>My best option so far is to use Trace, which feels like a bad hack.</p>