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/postProcessing/dataConversion/foamToTetDualMesh/foamToTetDualMesh.C

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2023 OpenCFD Ltd.
+    Copyright (C) 2023-2024 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -36,6 +36,7 @@ Description
 \*---------------------------------------------------------------------------*/
 
 #include "argList.H"
+#include "timeSelector.H"
 #include "fvMesh.H"
 #include "volFields.H"
 #include "pointFields.H"
@@ -145,20 +146,22 @@ void ReadAndMapFields
 
 int main(int argc, char *argv[])
 {
+    argList::noFunctionObjects();           // Never use function objects
+
+    timeSelector::addOptions_singleTime();  // Single-time options
+
     argList::addNote
     (
         "Convert polyMesh results to tetDualMesh"
     );
 
     #include "addOverwriteOption.H"
-    #include "addTimeOptions.H"
 
     #include "setRootCase.H"
     #include "createTime.H"
-    // Get times list
-    instantList Times = runTime.times();
-    #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);
 
     // Read the mesh
     #include "createNamedMesh.H"

applications/utilities/postProcessing/lumped/lumpedPointMovement/lumpedPointMovement.C

@@ -353,7 +353,7 @@ int main(int argc, char *argv[])
 
     #include "createTime.H"
 
-    runTime.setTime(instant(runTime.constant()), 0);
+    runTime.setTime(instant(0, runTime.constant()), 0);
 
     #include "createNamedMesh.H"
 

applications/utilities/postProcessing/lumped/lumpedPointZones/lumpedPointZones.C

@@ -106,7 +106,7 @@ int main(int argc, char *argv[])
     }
 
 
-    runTime.setTime(instant(runTime.constant()), 0);
+    runTime.setTime(instant(0, runTime.constant()), 0);
 
     #include "createNamedMesh.H"