[ML] Make constants truly constant (#411)

Follow-on to #102.  Fixing more places where pointers intended
to be immutable could be changed to a point at a different
constant.

Backport of #409

Author: droberts195

lib/api/CDataFrameAnalysisSpecification.cc

@@ -36,16 +36,16 @@ TRunnerFactoryUPtrVec analysisFactories() {
 }
 
 // These must be consistent with Java names.
-const char* ROWS{"rows"};
-const char* COLS{"cols"};
-const char* MEMORY_LIMIT{"memory_limit"};
-const char* THREADS{"threads"};
-const char* TEMPORARY_DIRECTORY{"temp_dir"};
-const char* ANALYSIS{"analysis"};
-const char* NAME{"name"};
-const char* PARAMETERS{"parameters"};
-
-const char* VALID_MEMBER_NAMES[]{ROWS, COLS, MEMORY_LIMIT, THREADS, ANALYSIS};
+const char* const ROWS{"rows"};
+const char* const COLS{"cols"};
+const char* const MEMORY_LIMIT{"memory_limit"};
+const char* const THREADS{"threads"};
+const char* const TEMPORARY_DIRECTORY{"temp_dir"};
+const char* const ANALYSIS{"analysis"};
+const char* const NAME{"name"};
+const char* const PARAMETERS{"parameters"};
+
+const char* const VALID_MEMBER_NAMES[]{ROWS, COLS, MEMORY_LIMIT, THREADS, ANALYSIS};
 
 template<typename MEMBER>
 bool isValidMember(const MEMBER& member) {

lib/api/CDataFrameOutliersRunner.cc

@@ -27,16 +27,16 @@ namespace ml {
 namespace api {
 namespace {
 // Configuration
-const char* NUMBER_NEIGHBOURS{"number_neighbours"};
-const char* METHOD{"method"};
-const char* LOF{"lof"};
-const char* LDOF{"ldof"};
-const char* DISTANCE_KTH_NN{"distance_kth_nn"};
-const char* DISTANCE_KNN{"distance_knn"};
-const char* VALID_MEMBER_NAMES[]{NUMBER_NEIGHBOURS, METHOD};
+const char* const NUMBER_NEIGHBOURS{"number_neighbours"};
+const char* const METHOD{"method"};
+const char* const LOF{"lof"};
+const char* const LDOF{"ldof"};
+const char* const DISTANCE_KTH_NN{"distance_kth_nn"};
+const char* const DISTANCE_KNN{"distance_knn"};
+const char* const VALID_MEMBER_NAMES[]{NUMBER_NEIGHBOURS, METHOD};
 
 // Output
-const char* OUTLIER_SCORE{"outlier_score"};
+const char* const OUTLIER_SCORE{"outlier_score"};
 
 template<typename MEMBER>
 bool isValidMember(const MEMBER& member) {

lib/config/CTools.cc

@@ -85,7 +85,7 @@ std::string CTools::prettyPrint(double d) {
 }
 
 std::string CTools::prettyPrint(core_t::TTime time) {
-    static const char* SUFFIXES[] = {" week", " day", " hr", " min", " sec"};
+    static const char* const SUFFIXES[] = {" week", " day", " hr", " min", " sec"};
 
     std::string result;
     core_t::TTime intervals[] = {(time / 604800), (time / 86400) % 7,