Minor API change to fix problem in wrapper generation

openmmapi/include/openmm/CustomIntegrator.h

@@ -233,7 +233,7 @@ public:
      * @param index    the index of the variable to get
      * @return the name of the variable
      */
-    std::string getGlobalVariableName(int index) const;
+    const std::string& getGlobalVariableName(int index) const;
     /**
      * Define a new per-DOF variable.
      * 
@@ -249,7 +249,7 @@ public:
      * @param index    the index of the variable to get
      * @return the name of the variable
      */
-    std::string getPerDofVariableName(int index) const;
+    const std::string& getPerDofVariableName(int index) const;
     /**
      * Get the current value of a global variable.
      * 

openmmapi/src/CustomIntegrator.cpp

@@ -84,7 +84,7 @@ int CustomIntegrator::addGlobalVariable(const string& name, double initialValue)
     return globalNames.size()-1;
 }
 
-string CustomIntegrator::getGlobalVariableName(int index) const {
+const string& CustomIntegrator::getGlobalVariableName(int index) const {
     if (index < 0 || index >= globalNames.size())
         throw OpenMMException("Index out of range");
     return globalNames[index];
@@ -98,7 +98,7 @@ int CustomIntegrator::addPerDofVariable(const string& name, double initialValue)
     return perDofNames.size()-1;
 }
 
-string CustomIntegrator::getPerDofVariableName(int index) const {
+const string& CustomIntegrator::getPerDofVariableName(int index) const {
     if (index < 0 || index >= perDofNames.size())
         throw OpenMMException("Index out of range");
     return perDofNames[index];