SGDOptimizer BS constructor implemented;

abstracted out from DoTrain() creation of objects, with two versions one for old CNTK config, and one for BS

Common/Include/ScriptableObjects.h

@@ -373,7 +373,6 @@ namespace Microsoft { namespace MSR { namespace ScriptableObjects {
         bool Exists(const wstring & id) const { return Find(id) != nullptr; }
         static const IConfigRecord & Record();
         template<class V> static const std::vector<typename V::value_type> & Array(const V & vec);
-
     };
     typedef shared_ptr<struct IConfigRecord> IConfigRecordPtr;
 

MachineLearning/CNTK/CNTK.cpp

@@ -850,6 +850,21 @@ function<ComputationNetworkPtr(DEVICEID_TYPE)> GetCreateNetworkFn(const Scriptab
 }
 function<ComputationNetworkPtr(DEVICEID_TYPE)> GetCreateNetworkFn(const ConfigParameters &) { NOT_IMPLEMENTED; }  // old CNTK config does not support lambdas
 
+// function to create an object of a certain type, using both old CNTK config and BrainScript
+template<class C>
+shared_ptr<C> CreateObject(const ScriptableObjects::IConfigRecord & config, const wchar_t * id)
+{
+    // TODO: CNTK config added "traceLevel = 0" to 'config'. In BS, we cannot do that (IConfigRecord is immutable). Solution: Just say "traceLevel = 0" in the BS macros for readers.
+    return config[id].AsPtr<C>();       // BS instantiates this object through this call
+}
+template<class C>
+shared_ptr<C> CreateObject(const ConfigParameters & config, const wchar_t * id)
+{
+    ConfigParameters readerConfig(config(id));
+    readerConfig.Insert("traceLevel", config(L"traceLevel", "0"));        // TODO: fix this by adding it to all config blocks. Easy to fix in BS as 'config with [ traceLevel = 0 ]'.
+    return make_shared<C>(readerConfig); // old CNTK config specifies a dictionary which then must be explicitly instantiated
+}
+
 template <class ConfigRecordType, typename ElemType>
 void DoTrain(const ConfigRecordType & config)
 {
@@ -913,23 +928,24 @@ void DoTrain(const ConfigRecordType & config)
         RuntimeError("No network builder found in the config file. NDLNetworkBuilder or SimpleNetworkBuilde must be specified");
     }
 
-    // BUGBUG: inconsistency with BrainScript: old config passes a config dict, whereas BrainScript creates the object right away
-    const ConfigRecordType & readerConfig(config(L"reader"));
-    //readerConfig.Insert("traceLevel", config(L"traceLevel", "0"));        // TODO: fix this by adding it to all config blocks. Easy to fix in BS as 'config with [ traceLevel = 0 ]'.
-    auto dataReader = make_shared<DataReader<ElemType>>(readerConfig);
+    auto dataReader = CreateObject<DataReader<ElemType>>(config, L"reader");
 
     shared_ptr<DataReader<ElemType>> cvDataReader;
     if (config.Exists(L"cvReader"))
+        cvDataReader = CreateObject<DataReader<ElemType>>(config, L"cvReader");
+
+    shared_ptr<SGD<ElemType>> optimizer;
+    if (config.Exists(L"optimizer"))
     {
-        const ConfigRecordType & cvReaderConfig(config(L"cvReader"));
-        //cvReaderConfig.Insert("traceLevel", config(L"traceLevel", "0"));
-        cvDataReader = unique_ptr<DataReader<ElemType> >{ new DataReader<ElemType>(cvReaderConfig) };
+        optimizer = CreateObject<SGD<ElemType>>(config, L"optimizer");
+    }
+    else // legacy CNTK config syntax: needs a record called 'SGD'
+    {
+        const ConfigRecordType & configSGD(config(L"SGD"));
+        optimizer = make_shared<SGD<ElemType>>(SGDParams(configSGD, sizeof(ElemType)));
     }
 
-    const ConfigRecordType & configSGD(config(L"SGD"));
-    SGD<ElemType> sgd(SGDParams(configSGD, sizeof(ElemType)));
-
-    sgd.Train(createNetworkFn, deviceId, dataReader.get(), cvDataReader.get(), makeMode);
+    optimizer->Train(createNetworkFn, deviceId, dataReader.get(), cvDataReader.get(), makeMode);
 }
 
 namespace Microsoft { namespace MSR { namespace ScriptableObjects {

MachineLearning/CNTKSGDLib/SGD.cpp

@@ -2621,7 +2621,7 @@ namespace Microsoft { namespace MSR { namespace CNTK {
     template class SGD<float>;
     template class SGD<double>;
 
-    // register ComputationNode with the ScriptableObject system
-    ScriptableObjects::ConfigurableRuntimeTypeRegister::Add<SGDParams> registerComputationNode(L"SGDParams");
+    // register SGD<> with the ScriptableObject system
+    ScriptableObjects::ConfigurableRuntimeTypeRegister::AddFloatDouble<SGD<float>,SGD<double>> registerSGDOptimizer(L"SGDOptimizer");
 
 }}}

MachineLearning/CNTKSGDLib/SGD.h

@@ -263,6 +263,10 @@ class SGD : public SGDParams
     { }
     // note: This must be in the header, as we cannot properly specialize this constructor in the CPP to make sure all versions are generated.
 
+    SGD(const ScriptableObjects::IConfigRecordPtr configp) :
+        SGD(*configp)
+    { }
+
     SGD(SGDParams&& sgdParams);
 
     void Train(function<ComputationNetworkPtr(DEVICEID_TYPE)> createNetworkFn, DEVICEID_TYPE deviceId,