Add DDim::size()

paddle/framework/ddim.cc

@@ -117,6 +117,8 @@ int DDim::operator[](int idx) const {
   return boost::apply_visitor(DynamicConstIndexer(idx), var);
 }
 
+ssize_t DDim::size() const { return arity(*this); }
+
 bool DDim::operator==(DDim d) const {
   if (var.which() != d.getVar().which()) {
     return false;

paddle/framework/ddim.h

@@ -50,6 +50,8 @@ struct DDim {
 
   DDimVar getVar() { return var; }
 
+  ssize_t size() const;
+
   bool operator==(DDim d) const;
 
   bool operator!=(DDim d) const;

paddle/framework/ddim_test.cc

@@ -49,6 +49,7 @@ TEST(DDim, Equality) {
 
   // arity of a DDim
   EXPECT_EQ(paddle::framework::arity(ddim), 3);
+  EXPECT_EQ(ddim.size(), 3);
 
   // product of a DDim
   EXPECT_EQ(paddle::framework::product(vddim), 45);