Nice unification.

I also considered just changing the SetUp method to be implemented only in the Layer superclass and just have that method call CheckBlobCounts and FurtherSetUp

Since the blob check should be done for every SetUp, I like this design. There's no need for the additional call from Net::Init or elsewhere should SetUp be called -- as fancy layers might that have their own internal layers. Changing the name to FurtherSetup is a little awkward though. Perhaps Layer::SetUp could not be virtual but each layer's SetUp could call the base class's? This isn't totally automatic, but is still concise. This would also allow for a layer that has more complicated blob checking rules that somehow don't fit into exact/min/max (not that I expect that to come up...).

Thoughts?

Yeah, I'd also thought about having each layer make the call to the parent explicitly, but went this way because (as you said) it's more automatic. But I think you're right, it's safer not to have to remember to make an additional call everywhere SetUp is called, so I'll do it that way. Thanks.

Re-implemented as suggested (with base Layer::SetUp calling CheckBlobCounts and each Layer subclass explicitly calling Layer::SetUp). Please take another look when you get a chance, @shelhamer.

Once again, nice tidying up. Thanks Jeff!

Thanks for noticing that @sguada. I pushed the fix for the bottom blob count directly to dev (see below), but it seems to only support 1 top blob currently (and was previously checking as such) so I left that as is.

[/home/jdonahue/dev/caffe 1]$ g show
commit e17b3fea57b6166a4cd65e604bf5e5e702c08c21
Author: Jeff Donahue <jeff.donahue@gmail.com>
Date:   Sun Jun 8 22:44:32 2014 -0700

    fix ArgMaxLayer bug in num bottom blobs decl. pointed out by @sguada

diff --git a/include/caffe/vision_layers.hpp b/include/caffe/vision_layers.hpp
index eb067bb..fc3dbbe 100644
--- a/include/caffe/vision_layers.hpp
+++ b/include/caffe/vision_layers.hpp
@@ -37,7 +37,7 @@ class ArgMaxLayer : public Layer<Dtype> {
   virtual inline LayerParameter_LayerType type() const {
     return LayerParameter_LayerType_ARGMAX;
   }
-  virtual inline int MinBottomBlobs() const { return 1; }
+  virtual inline int ExactNumBottomBlobs() const { return 1; }
   virtual inline int ExactNumTopBlobs() const { return 1; }

  protected: