Simplify initializer list constructors.

gtsam/inference/FactorGraph.h

@@ -166,10 +166,8 @@ class FactorGraph {
    *  FactorGraph fg = {make_shared<MyFactor>(), ...};
    */
   template <class DERIVEDFACTOR, typename = IsDerived<DERIVEDFACTOR>>
-  FactorGraph(
-      std::initializer_list<boost::shared_ptr<DERIVEDFACTOR>> sharedFactors) {
-    for (auto&& f : sharedFactors) factors_.push_back(f);
-  }
+  FactorGraph(std::initializer_list<boost::shared_ptr<DERIVEDFACTOR>> sharedFactors)
+      : factors_(sharedFactors) {}
 
   /// @}
   /// @name Adding Single Factors

gtsam/linear/VectorValues.h

@@ -92,11 +92,8 @@ namespace gtsam {
     VectorValues() {}
 
     /// Construct from initializer list.
-    VectorValues(std::initializer_list<std::pair<Key, Vector>> init) {
-      for (const auto& p : init) {
-        values_.insert(p);  // Insert key-value pair into map
-      }
-    }
+    VectorValues(std::initializer_list<std::pair<Key, Vector>> init)
+        : values_(init.begin(), init.end()) {}
 
     /** Merge two VectorValues into one, this is more efficient than inserting
      * elements one by one. */

gtsam/symbolic/SymbolicBayesNet.h

@@ -64,11 +64,8 @@ namespace gtsam {
      * Constructor that takes an initializer list of shared pointers.
      *  FactorGraph fg = {make_shared<MyFactor>(), ...};
      */
-    SymbolicBayesNet(
-        std::initializer_list<boost::shared_ptr<SymbolicConditional>>
-            sharedFactors) {
-      for (auto&& f : sharedFactors) factors_.push_back(f);
-    }
+    SymbolicBayesNet(std::initializer_list<boost::shared_ptr<SymbolicConditional>> sharedFactors)
+        : Base() {}
 
     /// Construct from a single conditional
     SymbolicBayesNet(SymbolicConditional&& c) {

gtsam/symbolic/SymbolicFactorGraph.h

@@ -91,10 +91,9 @@ namespace gtsam {
      * Constructor that takes an initializer list of shared pointers.
      *  FactorGraph fg = {make_shared<MyFactor>(), ...};
      */
-    SymbolicFactorGraph(std::initializer_list<boost::shared_ptr<SymbolicFactor>>
-                            sharedFactors) {
-        for (auto&& f : sharedFactors) factors_.push_back(f);
-    }
+    SymbolicFactorGraph(
+        std::initializer_list<boost::shared_ptr<SymbolicFactor>> sharedFactors)
+        : Base(sharedFactors) {}
 
     /// Construct from a single factor
     SymbolicFactorGraph(SymbolicFactor&& c) {