title: How to get a tensorflow op by name?
body: <p>You can get a tensor by name with <code>tf.get_default_graph().get_tensor_by_name("tensor_name:0")</code></p>
  
  <p>But can you get an operation, such as <code>Optimizer.minimize</code>, or an <code>enqueue</code> operation on a queue?</p>
  
  <p>In my first model I returned all tensors and ops I would need from a <code>build_model</code> function. But the list of tensors got ugly. In later models I tossed all tensors and ops in a dictionary for easier access. This time around I thought I'd just look up tensors by name as I needed them, but I don't know how to do that with ops.</p>
  
  <p>Or is there a better way to do this? I find various tensors and ops are needed all over the place. Training, inference code, test cases, hence the desire for a nice standard way of accessing the various parts of the graph without passing variables all over the place.</p>