Added static Simulation::IsPlatformAvailable method to check OpenMM platforms.

modules/mol/mm/doc/simulation.rst

@@ -60,7 +60,7 @@ mapped back to the attached structure at any time.
     :param filename:    Filename
     :type filename:     :class:`str`
 
-  .. method:: Load(filename)
+  .. staticmethod:: Load(filename)
 
     Loads a dumped simulation from disk. You have to make sure, that the provided 
     settings are consistent with those from the saved simulation. Undefined 
@@ -72,6 +72,18 @@ mapped back to the attached structure at any time.
     :type filename:     :class:`str`
     :type settings:     :class:`Settings`
 
+  .. staticmethod:: IsPlatformAvailable(settings)
+
+    :return: True, if platform defined in *settings* is available. Otherwise,
+             construction of a simulation object will fail with these settings.
+    :rtype:  :class:`bool`
+    
+    :param settings: Controls the parametrization of this class.
+                     Only :attr:`Settings.openmm_plugin_directory`,
+                     :attr:`Settings.custom_plugin_directory` and
+                     :attr:`Settings.platform` are relevant.
+    :type settings:  :class:`Settings`
+
   .. method:: ApplyLBFGS([tolerance=1.0,max_iterations=1000])
 
     Run minimization using the Limited-memory Broyden–Fletcher–Goldfarb–Shanno 

modules/mol/mm/pymod/export_simulation.cc

@@ -52,7 +52,11 @@ void export_Simulation()
     .def(init<const ost::mol::EntityHandle, const ost::mol::mm::SettingsPtr>())
     .def(init<const ost::mol::mm::TopologyPtr,const ost::mol::EntityHandle&,const ost::mol::mm::SettingsPtr>())
     .def("Save",&ost::mol::mm::Simulation::Save,(arg("filename")))
-    .def("Load",&ost::mol::mm::Simulation::Load,(arg("filename"))).staticmethod("Load")
+    .def("Load",&ost::mol::mm::Simulation::Load,(arg("filename")))
+    .staticmethod("Load")
+    .def("IsPlatformAvailable",&ost::mol::mm::Simulation::IsPlatformAvailable,
+         (arg("settings")))
+    .staticmethod("IsPlatformAvailable")
     .def("Steps",&ost::mol::mm::Simulation::Steps,(arg("steps")))
     .def("GetPositions",&ost::mol::mm::Simulation::GetPositions,(arg("enforce_periodic_box")=false, arg("in_angstrom")=true))
     .def("GetVelocities",&ost::mol::mm::Simulation::GetVelocities)

modules/mol/mm/src/simulation.cc

@@ -267,6 +267,24 @@ SimulationPtr Simulation::Load(const String& filename, SettingsPtr settings){
 }
 
 
+bool Simulation::IsPlatformAvailable(const SettingsPtr settings) {
+  // load settings-dependent plugin directories
+  EnsurePluginsLoaded(settings->openmm_plugin_directory);
+  EnsurePluginsLoaded(settings->custom_plugin_directory);
+  // check if OpenMM platform exists by checking all (this is fast..)
+  const Platform platform_id = settings->platform;
+  for (int i = 0; i < OpenMM::Platform::getNumPlatforms(); ++i) {
+    OpenMM::Platform& platform = OpenMM::Platform::getPlatform(i);
+    if (   (platform_id == Reference && platform.getName() == "Reference")
+        || (platform_id == OpenCL && platform.getName() == "OpenCL")
+        || (platform_id == CUDA && platform.getName() == "CUDA")
+        || (platform_id == CPU && platform.getName() == "CPU")) {
+      return true;
+    }
+  }
+  return false;
+}
+
 void Simulation::EnsurePluginsLoaded(const String& plugin_path) {
   // note: this is guaranteed to be constructed on first use only
   static std::set<String> already_loaded;

modules/mol/mm/src/simulation.hh

@@ -67,6 +67,8 @@ public:
 
   static SimulationPtr Load(const String& filename, SettingsPtr settings);
 
+  static bool IsPlatformAvailable(const SettingsPtr settings);
+
   ost::mol::EntityHandle GetEntity() { return ent_; }
 
   geom::Vec3List GetPositions(bool enforce_periodic_box = false, bool in_angstrom = true);