Python: add context manager implementation

python/lammps/core.py

@@ -416,9 +416,16 @@ class lammps(object):
   # shut-down LAMMPS instance
 
   def __del__(self):
-    if self.lmp and self.opened:
+    self.close()
-      self.lib.lammps_close(self.lmp)
+
-      self.opened = 0
+  # -------------------------------------------------------------------------
+  # context manager implementation
+
+  def __enter__(self):
+    return self
+
+  def __exit__(self, ex_type, ex_value, ex_traceback):
+    self.close()
 
   # -------------------------------------------------------------------------
 
@@ -445,7 +452,8 @@ class lammps(object):
 
     This is a wrapper around the :cpp:func:`lammps_close` function of the C-library interface.
     """
-    if self.opened: self.lib.lammps_close(self.lmp)
+    if self.lmp and self.opened:
+      self.lib.lammps_close(self.lmp)
     self.lmp = None
     self.opened = 0
 
@@ -454,9 +462,7 @@ class lammps(object):
   def finalize(self):
     """Shut down the MPI communication through the library interface by calling :cpp:func:`lammps_finalize`.
     """
-    if self.opened: self.lib.lammps_close(self.lmp)
+    self.close()
-    self.lmp = None
-    self.opened = 0
     self.lib.lammps_finalize()
 
   # -------------------------------------------------------------------------

unittest/python/python-open.py

@@ -50,6 +50,16 @@ class PythonOpen(unittest.TestCase):
         self.assertIsNot(lmp.lmp,None)
         self.assertEqual(lmp.opened,1)
 
+    def testContextManager(self):
+        """Automatically clean up LAMMPS instance"""
+        with lammps(name=self.machine) as lmp:
+            self.assertIsNot(lmp.lmp,None)
+            self.assertEqual(lmp.opened,1)
+            self.assertEqual(has_mpi and has_mpi4py,lmp.has_mpi4py)
+            self.assertEqual(has_mpi,lmp.has_mpi_support)
+        self.assertIsNone(lmp.lmp,None)
+        self.assertEqual(lmp.opened,0)
+
     @unittest.skipIf(not (has_mpi and has_mpi4py),"Skipping MPI test since LAMMPS is not parallel or mpi4py is not found")
     def testWithMPI(self):
         from mpi4py import MPI