（前两天这篇博客不小心被自己更改删除了，现在重新补上。）

Caffe版本一直在不停更新，新版本往往会包含一些新的layer，如果只想将该layer移植到自己工程的版本中，该怎么做呢？看到网上有关于添加新layer的教程：

1. Add a class declaration for your layer to the appropriate one of common_layers.hpp, data_layers.hpp, loss_layers.hpp, neuron_layers.hpp, or vision_layers.hpp. Include an inline implementation of type and the *Blobs() methods to specify blob number requirements. Omit the *_gpu declarations if you’ll only be implementing CPU code.
2. Implement your layer in layers/your_layer.cpp.
   • SetUp for initialization: reading parameters, allocating buffers, etc.
   • Forward_cpu for the function your layer computes
   • Backward_cpu for its gradient
3. (Optional) Implement the GPU versions Forward_gpu and Backward_gpu in layers/your_layer.cu.
4. Add your layer to proto/caffe.proto, updating the next available ID. Also declare parameters, if needed, in this file.
5. Make your layer createable by adding it to layer_factory.cpp.
6. Write tests in test/test_your_layer.cpp. Use test/test_gradient_check_util.hpp to check that your Forward and Backward implementations are in numerical agreement.

但是，这种方法并不一定对移植有用，以CropLayer为例，按照上述的方法肯定是行不通的，编译的过程中会反复出现关于函数DiagonalAffineMap的错误。查看版本更新记录：Crop layer for automatically aligning computations，可以发现，原来不只是添加两个文件那么简单的事情，按照版本更新的差异，逐个文件进行更改就可以使用。

因此，对于移植来说，直接搜索版本更新记录，是更加直接和高效的办法。