0021308: EDF 1923 SMESH: Remove hard-coded dependency of the external mesh plugins from the SMESH module

* Improve documentation for meshing plug-ins (in particular, dynamically added methods)

src/SMESH_SWIG/smesh.py

@@ -36,14 +36,21 @@ import geompy
 import smeshDC
 from smeshDC import *
 
+# retrieve SMESH engine in try/except block
+# to avoid problems in some cases, e.g. when generating documentation
+try:
     # get instance of class smeshDC
     smesh = salome.lcc.FindOrLoadComponent( "FactoryServer", "SMESH" )
     smesh.init_smesh( salome.myStudy, geompy.geom )
+except:
+    smesh = None
+    pass
 
-# load plugins
+# load plugins and add dynamically generated methods to Mesh class,
+# the same for for global variables declared by plug-ins
 from smeshDC import Mesh, algoCreator
 for pluginName in os.environ[ "SMESH_MeshersList" ].split( ":" ):
-
+    #
     pluginName += "DC"
     try:
         exec( "from %s import *" % pluginName )
@@ -60,10 +67,17 @@ for pluginName in os.environ["SMESH_MeshersList"].split(":"):
         if type( algo ).__name__ == 'classobj' and hasattr( algo, "meshMethod" ):
             if not hasattr( Mesh, algo.meshMethod ):
                 setattr( Mesh, algo.meshMethod, algoCreator() )
+                pass
             getattr( Mesh, algo.meshMethod ).add( algo )
+            pass
+        pass
+    pass
+del pluginName
 
-# Export the methods of smeshDC
+# export the methods of smeshDC
+if smesh:
     for k in dir( smesh ):
 	if k[0] == '_': continue
 	globals()[k] = getattr( smesh, k )
     del k
+    pass