basic pickling support

git-svn-id: http://root.cern.ch/svn/root/trunk@23239 27541ba8-7e3a-0410-8455-c3a389f83636

bindings/pyroot/src/Pythonize.cxx

@@ -14,6 +14,7 @@
 #include "Converters.h"
 #include "MemoryRegulator.h"
 #include "Adapters.h"
+#include "Utility.h"
 
 // ROOT
 #include "TClass.h"
@@ -30,6 +31,8 @@
 #include "TBranch.h"
 #include "TLeaf.h"
 
+#include "TBufferFile.h"
+
 // CINT
 #include "Api.h"
 
@@ -40,6 +43,9 @@
 #include <utility>
 
 
+//- data _______________________________________________________________________
+R__EXTERN PyObject* gRootModule;
+
 namespace {
 
 // for convenience
@@ -236,6 +242,33 @@ namespace {
       return CallPyObjMethod( self, "IsEqual", obj );
    }
 
+//____________________________________________________________________________
+   PyObject* TObjectReduce( PyObject*, PyObject* args )
+   {
+   // Turn the TObject derived into a character stream and return for pickle,
+   // together with the callable object that can restore the stream into a
+   // TObject derived instance.
+      ObjectProxy* self = 0;
+      if ( ! PyArg_ParseTuple( args,
+                const_cast< char* >( "O!:__reduce__" ), &ObjectProxy_Type, &self ) )
+         return 0;
+
+      TBufferFile buf( TBuffer::kWrite );
+      buf.WriteObject( (TObject*)self->GetObject() );
+
+   // use a string for the serialized result, as a python buffer will not copy
+   // the buffer contents
+      PyObject* res2 = PyTuple_New( 1 );
+      PyTuple_SET_ITEM( res2, 0, PyString_FromStringAndSize( buf.Buffer(), buf.Length() ) );
+
+      PyObject* result = PyTuple_New( 2 );
+      PyTuple_SET_ITEM( result, 0,
+         PyObject_GetAttrString( gRootModule, const_cast< char* >( "_TObject__expand__" ) ) );
+      PyTuple_SET_ITEM( result, 1, res2 );
+
+      return result;
+   }
+
 
 //- TClass behaviour -----------------------------------------------------------
    PyObject* TClassStaticCast( PyObject*, PyObject* args )
@@ -1627,6 +1660,10 @@ Bool_t PyROOT::Pythonize( PyObject* pyclass, const std::string& name )
       Utility::AddToClass( pyclass, "__cmp__", (PyCFunction) TObjectCompare );
       Utility::AddToClass( pyclass, "__eq__",  (PyCFunction) TObjectIsEqual );
 
+   // enable pickling
+      Utility::AddToClass( pyclass, "__reduce__",  (PyCFunction) TObjectReduce );
+      Utility::AddToClass( pyclass, "__expand__",  (PyCFunction) TObjectReduce );
+
       return kTRUE;
    }
 

bindings/pyroot/src/RootModule.cxx

@@ -23,6 +23,8 @@
 #include "TClass.h"
 #include "TObject.h"
 
+#include "TBufferFile.h"
+
 // Standard
 #include <string>
 
@@ -309,6 +311,23 @@ namespace {
       return BindObject_( 0, PyTuple_GET_ITEM( args, 0 ) );
    }
 
+//____________________________________________________________________________
+   PyObject* TObjectExpand( PyObject*, PyObject* args )
+   {
+   // This method and is a helper for pickling for TObject derived classes.
+      PyObject* pybuf = 0;
+      if ( ! PyArg_ParseTuple( args,
+                const_cast< char* >( "O!:__expand__" ), &PyString_Type, &pybuf ) )
+         return 0;
+
+   // use the PyString macro's to by-pass error checking; do not copy the buffer
+   // as the TBufferFile is local to this function only
+      TBufferFile buf( TBuffer::kRead,
+          PyString_GET_SIZE( pybuf ), PyString_AS_STRING( pybuf ), kFALSE );
+      TObject* result = buf.ReadObject( 0 );
+      return BindRootObject( result, result->IsA() );
+   }
+
 //____________________________________________________________________________
    PyObject* SetMemoryPolicy( PyObject*, PyObject* args )
    {
@@ -380,6 +399,8 @@ static PyMethodDef gPyROOTMethods[] = {
      METH_VARARGS, (char*) "Create an object of given type, from given address" },
    { (char*) "MakeNullPointer", (PyCFunction)MakeNullPointer,
      METH_VARARGS, (char*) "Create a NULL pointer of the given type" },
+   { (char*) "_TObject__expand__", (PyCFunction)TObjectExpand,
+     METH_VARARGS, (char*) "Helper method for pickling" },
    { (char*) "SetMemoryPolicy", (PyCFunction)SetMemoryPolicy,
      METH_VARARGS, (char*) "Determines object ownership model" },
    { (char*) "SetSignalPolicy", (PyCFunction)SetSignalPolicy,