ENH: add single-time handling to timeSelector

- the timeSelector is often used to select single or multiple times
  (eg, for post-processing). However, there are a few applications
  where only a *single* time should be selected and set.

  These are now covered by this type of use:

      timeSelector::addOptions_singleTime();  // Single-time options
      ...
      // Allow override of time from specified time options, or no-op
      timeSelector::setTimeIfPresent(runTime, args);

   In some cases, if can be desirable to force starting from the
   initial Time=0 when no time options have been specified:

      // Set time from specified time options, or force start from Time=0
      timeSelector::setTimeIfPresent(runTime, args, true);

   These changes make a number of includes redundant:

     * addTimeOptions.H
     * checkConstantOption.H
     * checkTimeOption.H
     * checkTimeOptions.H
     * checkTimeOptionsNoConstant.H

ENH: add time handling to setFields, setAlphaField (#3143)

    Co-authored-by: Johan Roenby <>

STYLE: replace instant("constant") with instant(0, "constant")

- avoids relying on atof parse behaviour returning zero

applications/utilities/mesh/manipulation/renumberMesh/renumberMesh.C

@@ -803,6 +803,10 @@ CompactListList<label> regionRenumber
 
 int main(int argc, char *argv[])
 {
+    argList::noFunctionObjects();           // Never use function objects
+
+    timeSelector::addOptions_singleTime();  // Single-time options
+
     argList::addNote
     (
         "Renumber mesh cells to reduce the bandwidth. Use the -lib option or"
@@ -863,11 +867,8 @@ int main(int argc, char *argv[])
         "eg, 'reverse true;'"
     );
 
-    argList::noFunctionObjects();  // Never use function objects
-
     #include "addAllRegionOptions.H"
     #include "addOverwriteOption.H"
-    #include "addTimeOptions.H"
 
     // -------------------------
 
@@ -926,14 +927,15 @@ int main(int argc, char *argv[])
     // Get region names
     #include "getAllRegionOptions.H"
 
-    // Get times list
-    instantList Times = runTime.times();
-
-    // Set startTime depending on -time and -latestTime options
-    #include "checkTimeOptions.H"
-
-    runTime.setTime(Times[startTime], startTime);
+    // Set time from specified time options, or force start from Time=0
+    timeSelector::setTimeIfPresent(runTime, args, true);
 
+    // Capture current time information for non-overwrite
+    const Tuple2<instant, label> startTime
+    (
+        instant(runTime.value(), runTime.timeName()),
+        runTime.timeIndex()
+    );
 
     // Start/reset all timings
     timer.resetTime();
@@ -947,7 +949,10 @@ int main(int argc, char *argv[])
     for (fvMesh& mesh : meshes)
     {
         // Reset time in case of multiple meshes and not overwrite
-        runTime.setTime(Times[startTime], startTime);
+        if (!overwrite)
+        {
+            runTime.setTime(startTime.first(), startTime.second());
+        }
 
         const word oldInstance = mesh.pointsInstance();
 

applications/utilities/mesh/manipulation/setsToZones/setsToZones.C

@@ -62,12 +62,13 @@ using namespace Foam;
 
 int main(int argc, char *argv[])
 {
+    timeSelector::addOptions_singleTime();  // Single-time options
+
     argList::addNote
     (
         "Add point/face/cell Zones from similarly named point/face/cell Sets"
     );
 
-    timeSelector::addOptions(true, false);  // constant(true), zero(false)
     argList::addBoolOption
     (
         "noFlipMap",
@@ -75,14 +76,13 @@ int main(int argc, char *argv[])
     );
 
     #include "addRegionOption.H"
-    #include "addTimeOptions.H"
     #include "setRootCase.H"
     #include "createTime.H"
 
     const bool noFlipMap = args.found("noFlipMap");
 
-    // Get times list
-    (void)timeSelector::selectIfPresent(runTime, args);
+    // Allow override of time from specified time options, or no-op
+    timeSelector::setTimeIfPresent(runTime, args);
 
     #include "createNamedPolyMesh.H"
 

applications/utilities/mesh/manipulation/topoSet/topoSet.C

@@ -240,9 +240,9 @@ int main(int argc, char *argv[])
     // Read set construct info from dictionary
     List<namedDictionary> actionEntries(topoSetDict.lookup("actions"));
 
-    forAll(timeDirs, timeI)
+    forAll(timeDirs, timei)
     {
-        runTime.setTime(timeDirs[timeI], timeI);
+        runTime.setTime(timeDirs[timei], timei);
         Info<< "Time = " << runTime.timeName() << endl;
 
         // Optionally re-read mesh