Add Init to OperatorBase (#2838)

paddle/framework/op_registry.h

@@ -119,6 +119,7 @@ class OpRegistry {
       op->attrs_[attr.name()] = AttrTypeHelper::GetAttrValue(attr);
     }
     op_checkers().at(op_type).Check(op->attrs_);
+    op->Init();
     return op;
   }
 

paddle/framework/operator.h

@@ -49,6 +49,10 @@ class OperatorBase {
 
   std::string DebugString() const;
 
+  /// Init will be called after CreateOperator, you can put some initialization
+  /// logic here.
+  virtual void Init() {}
+
   /// InferShape infer the size of Variables used by this Operator with
   /// information inside scope
   virtual void InferShape(const std::shared_ptr<Scope>& scope) const = 0;

paddle/framework/operator_test.cc

@@ -21,14 +21,19 @@ namespace framework {
 
 class OperatorTest : public OperatorBase {
  public:
+  void Init() override { x = 1; }
   void InferShape(const std::shared_ptr<Scope>& scope) const override {}
   void Run(const std::shared_ptr<Scope>& scope,
            const platform::DeviceContext& dev_ctx) const override {
     float scale = GetAttr<float>("scale");
     ASSERT_NEAR(scale, 3.14, 1e-5);
     ASSERT_EQ(scope->GetVariable(inputs_[0]), nullptr);
+    ASSERT_EQ(x, 1);
     ASSERT_NE(scope->GetVariable(outputs_[0]), nullptr);
   }
+
+ public:
+  float x = 0;
 };
 
 class OperatorTestProtoAndCheckerMaker : public OpProtoAndCheckerMaker {