Add active_writer_version, test writer activation functions

pyomo/repn/plugins/__init__.py

@@ -42,3 +42,18 @@ def activate_writer_version(name, ver):
     doc = WriterFactory.doc(name)
     WriterFactory.unregister(name)
     WriterFactory.register(name, doc)(WriterFactory.get_class(f'{name}_v{ver}'))
+
+
+def active_writer_version(name):
+    """DEBUGGING TOOL to switch the "default" writer implementation"""
+    from pyomo.opt import WriterFactory
+
+    ref = WriterFactory.get_class(name)
+    ver = 1
+    try:
+        while 1:
+            if WriterFactory.get_class(f'{name}_v{ver}') is ref:
+                return ver
+            ver += 1
+    except KeyError:
+        return None

pyomo/repn/tests/test_plugins.py

@@ -0,0 +1,50 @@
+#  ___________________________________________________________________________
+#
+#  Pyomo: Python Optimization Modeling Objects
+#  Copyright (c) 2008-2024
+#  National Technology and Engineering Solutions of Sandia, LLC
+#  Under the terms of Contract DE-NA0003525 with National Technology and
+#  Engineering Solutions of Sandia, LLC, the U.S. Government retains certain
+#  rights in this software.
+#  This software is distributed under the 3-clause BSD License.
+#  ___________________________________________________________________________
+
+from pyomo.common import unittest
+
+from pyomo.opt import WriterFactory
+from pyomo.repn.plugins import activate_writer_version, active_writer_version
+
+import pyomo.environ
+
+
+class TestPlugins(unittest.TestCase):
+    def test_active(self):
+        with self.assertRaises(KeyError):
+            active_writer_version('nonexistant_writer')
+        ver = active_writer_version('lp')
+        self.assertIs(
+            WriterFactory.get_class('lp'), WriterFactory.get_class(f'lp_v{ver}')
+        )
+
+        class TMP(object):
+            pass
+
+        WriterFactory.register('test_writer')(TMP)
+        try:
+            self.assertIsNone(active_writer_version('test_writer'))
+        finally:
+            WriterFactory.unregister('test_writer')
+
+    def test_activate(self):
+        ver = active_writer_version('lp')
+        try:
+            activate_writer_version('lp', 2)
+            self.assertIs(
+                WriterFactory.get_class('lp'), WriterFactory.get_class(f'lp_v2')
+            )
+            activate_writer_version('lp', 1)
+            self.assertIs(
+                WriterFactory.get_class('lp'), WriterFactory.get_class(f'lp_v1')
+            )
+        finally:
+            activate_writer_version('lp', ver)