[svn-r15482] Description:

    Added missing wrappers for H5Rdereference.
    Also, for these wrappers, improved exception handlings to report specific
        overloaded functions, where failure occurs.  Will do the same for more
        functions later...

Platforms tested:
    Linux 2.6 (kagiso)
    SunOS 5.10 (linew)
    FreeBSD (duty)

19 files changed, 367 insertions, 180 deletions

diff --git a/c++/src/H5AbstractDs.cpp b/c++/src/H5AbstractDs.cpp
index 26bf5ad..69b34f6 100644
--- a/c++/src/H5AbstractDs.cpp
+++ b/c++/src/H5AbstractDs.cpp
@@ -37,13 +37,6 @@ namespace H5 {
 AbstractDs::AbstractDs(){}
 
 //--------------------------------------------------------------------------
-// Function:	AbstractDs default constructor
-///\brief	Creates an AbstractDs instance using an existing id.
-// Programmer	Binh-Minh Ribler - 2000
-//--------------------------------------------------------------------------
-//AbstractDs::AbstractDs(const hid_t ds_id){}
-
-//--------------------------------------------------------------------------
 // Function:	AbstractDs copy constructor
 ///\brief	Copy constructor: makes a copy of the original AbstractDs object.
 // Programmer	Binh-Minh Ribler - 2000
diff --git a/c++/src/H5AbstractDs.h b/c++/src/H5AbstractDs.h
index 2d04b43..af8680e 100644
--- a/c++/src/H5AbstractDs.h
+++ b/c++/src/H5AbstractDs.h
@@ -75,9 +75,6 @@ class H5_DLLCPP AbstractDs {
 	// Default constructor
 	AbstractDs();
 
-	// Constructor that takes an attribute id or a dataset id.
-	//AbstractDs( const hid_t ds_id );
-
    private:
 	// This member function is implemented by DataSet and Attribute.
 	virtual hid_t p_get_type() const = 0;
diff --git a/c++/src/H5Attribute.cpp b/c++/src/H5Attribute.cpp
index 3f8fae9..8b42299 100644
--- a/c++/src/H5Attribute.cpp
+++ b/c++/src/H5Attribute.cpp
@@ -62,7 +62,7 @@ Attribute::Attribute() : AbstractDs(), IdComponent(), id(0) {}
 //	Jul, 08 No longer inherit data member 'id' from IdComponent.
 //		- bugzilla 1068
 //--------------------------------------------------------------------------
-Attribute::Attribute( const Attribute& original ) : AbstractDs(), IdComponent()
+Attribute::Attribute(const Attribute& original) : AbstractDs(), IdComponent()
 {
     id = original.getId();
     incRefCount(); // increment number of references to this id
@@ -160,6 +160,7 @@ void Attribute::read( const DataType& mem_type, void *buf ) const
 void Attribute::read( const DataType& mem_type, H5std_string& strg ) const
 {
    // Get the attribute size and allocate temporary C-string for C API
+   // NOTE: will be changed to use dataspace information instead of this API
    hsize_t attr_size = H5Aget_storage_size(id);
    if (attr_size <= 0)
    {
@@ -287,6 +288,7 @@ H5std_string Attribute::getName( size_t buf_size ) const
    H5std_string attr_name;
    ssize_t name_size = getName( buf_size, attr_name );
    return( attr_name );
+   // let caller catch exception if any
 }
 
 //--------------------------------------------------------------------------
@@ -300,7 +302,6 @@ H5std_string Attribute::getName( size_t buf_size ) const
 //--------------------------------------------------------------------------
 H5std_string Attribute::getName() const
 {
-
    // Try with 0 and NULL to get the name size
    ssize_t name_size = H5Aget_name(id, 0, NULL);
 
@@ -328,36 +329,6 @@ H5std_string Attribute::getName() const
    return(attr_name);
 }
 
-#if 0
-//--------------------------------------------------------------------------
-// Function:	Attribute::getObjType
-///\brief	Retrieves the type of object that an object reference points to.
-///\param	ref	 - IN: Reference to query
-///\param	ref_type - IN: Type of reference to query, valid values are:
-///		\li \c H5R_OBJECT \tReference is an object reference.
-///		\li \c H5R_DATASET_REGION \tReference is a dataset region reference.
-///\return	An object type, which can be one of the following:
-///		\li \c H5G_LINK (0) \tObject is a symbolic link.
-///		\li \c H5G_GROUP (1) \tObject is a group.
-///		\li \c H5G_DATASET (2) \tObject is a dataset.
-///		\li \c H5G_TYPE Object (3) \tis a named datatype
-///\exception	H5::AttributeIException
-// Programmer	Binh-Minh Ribler - Jul, 2008
-// Note:
-//		H5G_loc checks args in H5Rget_obj_type, so attribute must
-//		also be included.
-//--------------------------------------------------------------------------
-H5G_obj_t Attribute::getObjType(void *ref, H5R_type_t ref_type) const
-{
-   try {
-      return(p_get_refobj_type(ref, ref_type));
-   }
-   catch (IdComponentException E) {
-      throw AttributeIException("Attribute::getObjType", E.getDetailMsg());
-   }
-}
-#endif
-
 //--------------------------------------------------------------------------
 // Function:	Attribute::getRefObjType
 ///\brief	Retrieves the type of object that an object reference points to.
@@ -470,8 +441,10 @@ void Attribute::close()
 	{
 	    throw AttributeIException("Attribute::close", "H5Aclose failed");
 	}
-	// reset the id because the attribute that it represents is now closed
-	id = 0;
+	// reset the id when the attribute that it represents is no longer
+	// referenced
+	if (getCounter() == 0)
+	    id = 0;
     }
 }
 
diff --git a/c++/src/H5CommonFG.h b/c++/src/H5CommonFG.h
index e80857e..d9aa285 100644
--- a/c++/src/H5CommonFG.h
+++ b/c++/src/H5CommonFG.h
@@ -69,6 +69,11 @@ class H5_DLLCPP CommonFG {
 	// Returns the number of objects in this group.
 	hsize_t getNumObjs() const;
 
+	// Retrieves the name of an object in this group, given the
+	// object's index.
+	ssize_t getObjnameByIdx(hsize_t idx, H5std_string& name, size_t size) const;
+	H5std_string getObjnameByIdx(hsize_t idx) const;
+
 	// Returns the type of an object in this group, given the
 	// object's index.
 	H5G_obj_t getObjTypeByIdx(hsize_t idx) const;
@@ -81,11 +86,6 @@ class H5_DLLCPP CommonFG {
 	void getObjinfo(const char* name, H5G_stat_t& statbuf) const;
 	void getObjinfo(const H5std_string& name, H5G_stat_t& statbuf) const;
 
-	// Retrieves the name of an object in this group, given the
-	// object's index.
-	ssize_t getObjnameByIdx(hsize_t idx, H5std_string& name, size_t size) const;
-	H5std_string getObjnameByIdx(hsize_t idx) const;
-
 	// Iterates over the elements of this group - not implemented in
 	// C++ style yet.
 	int iterateElems(const char* name, int *idx, H5G_iterate_t op, void *op_data);
diff --git a/c++/src/H5DataSet.cpp b/c++/src/H5DataSet.cpp
index 0151107..0539484 100644
--- a/c++/src/H5DataSet.cpp
+++ b/c++/src/H5DataSet.cpp
@@ -35,6 +35,7 @@
 #include "H5DataSpace.h"
 #include "H5AbstractDs.h"
 #include "H5File.h"
+#include "H5Attribute.h"
 #include "H5DataSet.h"
 
 #ifndef H5_NO_NAMESPACE
@@ -66,7 +67,7 @@ DataSet::DataSet(const hid_t existing_id) : AbstractDs(), H5Object(), id(existin
 ///\param	original - IN: DataSet instance to copy
 // Programmer	Binh-Minh Ribler - 2000
 //--------------------------------------------------------------------------
-DataSet::DataSet(const DataSet& original) : AbstractDs(original), H5Object()
+DataSet::DataSet(const DataSet& original) : AbstractDs(original), H5Object(original)
 {
     id = original.getId();
     incRefCount(); // increment number of references to this id
@@ -74,24 +75,75 @@ DataSet::DataSet(const DataSet& original) : AbstractDs(original), H5Object()
 
 //--------------------------------------------------------------------------
 // Function:	DataSet overload constructor - dereference
-///\brief	Given a reference to some object, returns that dataset
+///\brief	Given a reference, ref, to an hdf5 dataset, creates a 
+///		DataSet object
 ///\param	obj - IN: Dataset reference object is in or location of
-///			object that the dataset is located within.
+///			  object that the dataset is located within.
 ///\param	ref - IN: Reference pointer
+///\param	ref_type - IN: Reference type - default to H5R_OBJECT
 ///\exception	H5::DataSetIException
 ///\par Description
 ///		\c obj can be DataSet, Group, H5File, or named DataType, that 
 ///		is a datatype that has been named by DataType::commit.
 // Programmer	Binh-Minh Ribler - Oct, 2006
+// Modification
+//	Jul, 2008
+//		Added for application convenience.
 //--------------------------------------------------------------------------
 DataSet::DataSet(H5Object& obj, void* ref, H5R_type_t ref_type) : AbstractDs(), H5Object()
 {
-   dereference(obj, ref, ref_type);
+    try {
+	id = p_dereference(obj.getId(), ref, ref_type);
+    } catch (ReferenceException deref_error) {
+	throw ReferenceException("DataSet constructor - located by object", 
+		deref_error.getDetailMsg());
+    }
 }
 
+//--------------------------------------------------------------------------
+// Function:	DataSet overload constructor - dereference
+///\brief	Given a reference, ref, to an hdf5 dataset, creates a 
+///		DataSet object
+///\param	h5file - IN: Location referenced object is in
+///\param	ref - IN: Reference pointer
+///\param	ref_type - IN: Reference type - default to H5R_OBJECT
+///\exception	H5::DataSetIException
+// Programmer	Binh-Minh Ribler - Oct, 2006
+// Modification
+//	Jul, 2008
+//		Added for application convenience.
+//--------------------------------------------------------------------------
 DataSet::DataSet(H5File& h5file, void* ref, H5R_type_t ref_type) : AbstractDs(), H5Object()
 {
-   dereference(h5file, ref, ref_type);
+    try {
+	id = p_dereference(h5file.getId(), ref, ref_type);
+    } catch (ReferenceException deref_error) {
+	throw ReferenceException("DataSet constructor - located by HDF5 file", 
+		deref_error.getDetailMsg());
+    }
+}
+
+//--------------------------------------------------------------------------
+// Function:	DataSet overload constructor - dereference
+///\brief	Given a reference, ref, to an hdf5 dataset, creates a 
+///		DataSet object
+///\param	attr - IN: Specifying location where the referenced object is in
+///\param	ref - IN: Reference pointer
+///\param	ref_type - IN: Reference type - default to H5R_OBJECT
+///\exception	H5::ReferenceException
+// Programmer	Binh-Minh Ribler - Oct, 2006
+// Modification
+//	Jul, 2008
+//		Added for application convenience.
+//--------------------------------------------------------------------------
+DataSet::DataSet(Attribute& attr, void* ref, H5R_type_t ref_type) : AbstractDs(), H5Object()
+{
+    try {
+	id = p_dereference(attr.getId(), ref, ref_type);
+    } catch (ReferenceException deref_error) {
+	throw ReferenceException("DataSet constructor - located by attribute", 
+		deref_error.getDetailMsg());
+    }
 }
 
 //--------------------------------------------------------------------------
@@ -586,8 +638,10 @@ void DataSet::close()
 	{
 	    throw DataSetIException("DataSet::close", "H5Dclose failed");
 	}
-	// reset the id because the dataset that it represents is now closed
-	id = 0;
+	// reset the id when the dataset that it represents is no longer
+	// referenced
+	if (getCounter() == 0)
+	    id = 0;
     }
 }
 
@@ -607,7 +661,7 @@ DataSet::~DataSet()
 	close();
     }
     catch (Exception close_error) {
-	cerr << "DataSet::~DataSet" << close_error.getDetailMsg() << endl;
+	cerr << "DataSet::~DataSet - " << close_error.getDetailMsg() << endl;
     }
 }
 
diff --git a/c++/src/H5DataSet.h b/c++/src/H5DataSet.h
index 2d625f0..87156ff 100644
--- a/c++/src/H5DataSet.h
+++ b/c++/src/H5DataSet.h
@@ -84,7 +84,8 @@ class H5_DLLCPP DataSet : public H5Object, public AbstractDs {
 
 	// Creates a dataset by way of dereference.
 	DataSet(H5Object& obj, void* ref, H5R_type_t ref_type = H5R_OBJECT);
-	DataSet(H5File& file, void* ref, H5R_type_t ref_type = H5R_OBJECT);
+	DataSet(H5File& h5file, void* ref, H5R_type_t ref_type = H5R_OBJECT);
+	DataSet(Attribute& attr, void* ref, H5R_type_t ref_type = H5R_OBJECT);
 
 	// Default constructor.
 	DataSet();
diff --git a/c++/src/H5DataSpace.cpp b/c++/src/H5DataSpace.cpp
index e755685..902513b 100644
--- a/c++/src/H5DataSpace.cpp
+++ b/c++/src/H5DataSpace.cpp
@@ -609,8 +609,10 @@ void DataSpace::close()
 	{
 	    throw DataSpaceIException("DataSpace::close", "H5Sclose failed");
 	}
-	// reset the id because the dataspace that it represents is now closed
-	id = 0;
+	// reset the id when the dataspace that it represents is no longer
+	// referenced
+	if (getCounter() == 0)
+	    id = 0;
     }
 }
 
diff --git a/c++/src/H5DataType.cpp b/c++/src/H5DataType.cpp
index 96adf8e..badefc2 100644
--- a/c++/src/H5DataType.cpp
+++ b/c++/src/H5DataType.cpp
@@ -38,6 +38,7 @@
 #include "H5AbstractDs.h"
 #include "H5DataSet.h"
 #include "H5File.h"
+#include "H5Attribute.h"
 
 #ifndef H5_NO_NAMESPACE
 namespace H5 {
@@ -85,22 +86,74 @@ DataType::DataType( const H5T_class_t type_class, size_t size ) : H5Object()
 
 //--------------------------------------------------------------------------
 // Function:	DataType overload constructor - dereference
-///\brief	Given a reference to some object, returns that datatype
-///\param       obj - IN: Location reference object is in
+///\brief	Given a reference, ref, to an hdf5 group, creates a
+///		DataType object
+///\param       obj - IN: Specifying location referenced object is in
 ///\param	ref - IN: Reference pointer
+///\param	ref_type - IN: Reference type - default to H5R_OBJECT
+///\exception	H5::ReferenceException
 ///\par Description
-///		\c obj can be DataSet, Group, H5File, or named DataType, that 
+///		\c obj can be DataSet, Group, or named DataType, that 
 ///		is a datatype that has been named by DataType::commit.
 // Programmer	Binh-Minh Ribler - Oct, 2006
+// Modification
+//	Jul, 2008
+//		Added for application convenience.
 //--------------------------------------------------------------------------
 DataType::DataType(H5Object& obj, void* ref, H5R_type_t ref_type) : H5Object()
 {
-   dereference(obj, ref, ref_type);
+    try {
+	id = p_dereference(obj.getId(), ref, ref_type);
+    } catch (ReferenceException deref_error) {
+	throw ReferenceException("DataType constructor - located by an H5Object",
+		deref_error.getDetailMsg());
+    }
 }
 
+//--------------------------------------------------------------------------
+// Function:	DataType overload constructor - dereference
+///\brief	Given a reference, ref, to an hdf5 group, creates a
+///		DataType object
+///\param       h5file - IN: Location referenced object is in
+///\param	ref - IN: Reference pointer
+///\param	ref_type - IN: Reference type - default to H5R_OBJECT
+///\exception	H5::ReferenceException
+// Programmer	Binh-Minh Ribler - Oct, 2006
+// Modification
+//	Jul, 2008
+//		Added for application convenience.
+//--------------------------------------------------------------------------
 DataType::DataType(H5File& h5file, void* ref, H5R_type_t ref_type) : H5Object()
 {
-   dereference(h5file, ref, ref_type);
+    try {
+	id = p_dereference(h5file.getId(), ref, ref_type);
+    } catch (ReferenceException deref_error) {
+	throw ReferenceException("DataType constructor - located by an H5File",
+		deref_error.getDetailMsg());
+    }
+}
+
+//--------------------------------------------------------------------------
+// Function:	DataType overload constructor - dereference
+///\brief	Given a reference, ref, to an hdf5 group, creates a
+///		DataType object
+///\param       attr - IN: Specifying location where the referenced object is in
+///\param	ref - IN: Reference pointer
+///\param	ref_type - IN: Reference type - default to H5R_OBJECT
+///\exception	H5::ReferenceException
+// Programmer	Binh-Minh Ribler - Oct, 2006
+// Modification
+//	Jul, 2008
+//		Added for application convenience.
+//--------------------------------------------------------------------------
+DataType::DataType(Attribute& attr, void* ref, H5R_type_t ref_type) : H5Object()
+{
+    try {
+	id = p_dereference(attr.getId(), ref, ref_type);
+    } catch (ReferenceException deref_error) {
+	throw ReferenceException("DataType constructor - located by an Attribute",
+		deref_error.getDetailMsg());
+    }
 }
 
 //--------------------------------------------------------------------------
@@ -769,8 +822,10 @@ void DataType::close()
 	{
 	    throw DataTypeIException(inMemFunc("close"), "H5Tclose failed");
 	}
-	// reset the id because the datatype that it represents is now closed
-	id = 0;
+        // reset the id when the datatype that it represents is no longer
+        // referenced
+        if (getCounter() == 0)
+	    id = 0;
     }
 }
 
diff --git a/c++/src/H5DataType.h b/c++/src/H5DataType.h
index 57a0345..cb7aa22 100644
--- a/c++/src/H5DataType.h
+++ b/c++/src/H5DataType.h
@@ -31,7 +31,8 @@ class H5_DLLCPP DataType : public H5Object {
 
 	// Creates a datatype by way of dereference.
 	DataType(H5Object& obj, void* ref, H5R_type_t ref_type = H5R_OBJECT);
-	DataType(H5File& file, void* ref, H5R_type_t ref_type = H5R_OBJECT);
+	DataType(H5File& h5file, void* ref, H5R_type_t ref_type = H5R_OBJECT);
+	DataType(Attribute& attr, void* ref, H5R_type_t ref_type = H5R_OBJECT);
 
 	// Closes this datatype.
 	virtual void close();
diff --git a/c++/src/H5DcreatProp.cpp b/c++/src/H5DcreatProp.cpp
index 656956f..c13f1be 100644
--- a/c++/src/H5DcreatProp.cpp
+++ b/c++/src/H5DcreatProp.cpp
@@ -343,14 +343,14 @@ int DSetCreatPropList::getNfilters() const
 //--------------------------------------------------------------------------
 // Function:	DSetCreatPropList::getFilter
 ///\brief	Returns information about a filter in a pipeline
-///\param	filter_number  - IN: Filter to get, range [0..N-1], where
-///				     N is returned by H5Pget_nfilters()
-///\param	flags         - OUT: General properties of the filter
-///\param	cd_nelmts  - IN/OUT: Number of elements in \a cd_values /Number
-///				     of values defined by the filter
-///\param	cd_values     - OUT: Array to hold the data; allocated by the user
-///\param	namelen       - OUT: Length of \a name
-///\param	name          - OUT: Name of the filter
+///\param	filter_number - IN: Filter to get, range [0..N-1], where
+///				N is returned by H5Pget_nfilters()
+///\param	flags     - OUT: General properties of the filter
+///\param	cd_nelmts - IN/OUT: Number of elements in \a cd_values /Number
+///				of values defined by the filter
+///\param	cd_values - OUT: Array to hold the data; allocated by the user
+///\param	namelen   - OUT: Length of \a name
+///\param	name      - OUT: Name of the filter
 ///\return	Filter id
 ///\exception	H5::PropListIException
 ///\par Description
diff --git a/c++/src/H5DxferProp.cpp b/c++/src/H5DxferProp.cpp
index 49cad88..ab76e49 100644
--- a/c++/src/H5DxferProp.cpp
+++ b/c++/src/H5DxferProp.cpp
@@ -31,7 +31,7 @@ namespace H5 {
 const DSetMemXferPropList DSetMemXferPropList::DEFAULT;
 
 //--------------------------------------------------------------------------
-// Function     DSetMemXferPropList default constructor
+// Function	DSetMemXferPropList default constructor
 ///\brief	Default constructor: creates a stub dataset memory and
 ///		transfer property list object.
 // Programmer:	Binh-Minh Ribler - 2000
diff --git a/c++/src/H5File.cpp b/c++/src/H5File.cpp
index 8931021..4a48e38 100644
--- a/c++/src/H5File.cpp
+++ b/c++/src/H5File.cpp
@@ -252,7 +252,7 @@ void H5File::openFile(const H5std_string& name, unsigned int flags, const FileAc
 //		If this object has represented another HDF5 file, the previous
 //		HDF5 file need to be closed first.
 // Programmer	Binh-Minh Ribler - 2000
-// Note:        This wrapper doesn't seem right regarding the 'id' and should
+// Note:	This wrapper doesn't seem right regarding the 'id' and should
 //              be investigated.  BMR - 2/20/2005
 // Modification
 //		- Replaced resetIdComponent() with decRefCount() to use C
@@ -586,7 +586,7 @@ hsize_t H5File::getFileSize() const
 
 //--------------------------------------------------------------------------
 // Function:    H5File::p_reference (protected)
-// Purpose      Creates a reference to an HDF5 object or a dataset region.
+// Purpose:	Creates a reference to an HDF5 object or a dataset region.
 // Parameters
 //              name - IN: Name of the object to be referenced
 //              dataspace - IN: Dataspace with selection
@@ -667,7 +667,7 @@ void H5File::reference(void* ref, const H5std_string& name) const
 #if 0
 //--------------------------------------------------------------------------
 // Function:    H5File::p_get_obj_type (protected)
-// Purpose      Retrieves the type of object that an object reference points to.
+// Purpose:	Retrieves the type of object that an object reference points to.
 // Parameters
 //              ref      - IN: Reference to query
 //              ref_type - IN: Type of reference to query
@@ -700,7 +700,7 @@ H5G_obj_t H5Object::p_get_obj_type(void *ref, H5R_type_t ref_type) const
 #endif
 //--------------------------------------------------------------------------
 // Function:    H5File::p_get_region (protected)
-// Purpose      Retrieves a dataspace with the region pointed to selected.
+// Purpose:	Retrieves a dataspace with the region pointed to selected.
 // Parameters
 //              ref_type - IN: Type of reference to get region of - default
 //                              to H5R_DATASET_REGION
@@ -789,8 +789,10 @@ void H5File::close()
 	{
 	    throw FileIException("H5File::close", "H5Fclose failed");
 	}
-	// reset the id because the file that it represents is now closed
-	id = 0;
+	// reset the id when the file that it represents is no longer
+	// referenced
+	if (getCounter() == 0)
+	    id = 0;
     }
 }
 
diff --git a/c++/src/H5Group.cpp b/c++/src/H5Group.cpp
index 16b0fee..47750e7 100644
--- a/c++/src/H5Group.cpp
+++ b/c++/src/H5Group.cpp
@@ -33,6 +33,7 @@
 #include "H5DataSpace.h"
 #include "H5DataSet.h"
 #include "H5CommonFG.h"
+#include "H5Attribute.h"
 #include "H5Group.h"
 #include "H5File.h"
 #include "H5Alltypes.h"
@@ -50,7 +51,7 @@ namespace H5 {
 ///\brief	Default constructor: creates a stub Group.
 // Programmer	Binh-Minh Ribler - 2000
 // Modification
-//	2008 08	No longer inherit data member 'id' from IdComponent.
+//	Jul, 08	No longer inherit data member 'id' from IdComponent.
 //		- bugzilla 1068
 //--------------------------------------------------------------------------
 Group::Group() : H5Object(), id(0) {}
@@ -97,22 +98,62 @@ Group::Group(const hid_t existing_id) : H5Object()
 
 //--------------------------------------------------------------------------
 // Function:	Group overload constructor - dereference
-///\brief	Given a reference to some object or a file, returns that group
-///\param	obj - IN: Location reference object is in
-///		ref - IN: Reference pointer
+///\brief	Given a reference, ref, to an hdf5 group, creates a Group object
+///\param	obj - IN: Specifying location referenced object is in
+///\param	ref - IN: Reference pointer
+///\param	ref_type - IN: Reference type - default to H5R_OBJECT
+///\exception	H5::ReferenceException
 ///\par Description
-///		\c obj can be DataSet, Group, H5File, or named DataType, that 
+///		\c obj can be DataSet, Group, or named DataType, that 
 ///		is a datatype that has been named by DataType::commit.
 // Programmer	Binh-Minh Ribler - Oct, 2006
 //--------------------------------------------------------------------------
 Group::Group(H5Object& obj, void* ref, H5R_type_t ref_type) : H5Object()
 {
-   dereference(obj, ref, ref_type);
+    try {
+	id = p_dereference(obj.getId(), ref, ref_type);
+    } catch (ReferenceException deref_error) {
+	throw ReferenceException("Group constructor - located by an H5Object",
+		deref_error.getDetailMsg());
+    }
 }
 
+//--------------------------------------------------------------------------
+// Function:	Group overload constructor - dereference
+///\brief	Given a reference, ref, to an hdf5 group, creates a Group object
+///\param	h5file - IN: Location referenced object is in
+///\param	ref - IN: Reference pointer
+///\param	ref_type - IN: Reference type - default to H5R_OBJECT
+///\exception	H5::ReferenceException
+// Programmer	Binh-Minh Ribler - Oct, 2006
+//--------------------------------------------------------------------------
 Group::Group(H5File& h5file, void* ref, H5R_type_t ref_type) : H5Object()
 {
-   dereference(h5file, ref, ref_type);
+    try {
+	id = p_dereference(h5file.getId(), ref, ref_type);
+    } catch (ReferenceException deref_error) {
+	throw ReferenceException("Group constructor - located by an H5File",
+		deref_error.getDetailMsg());
+    }
+}
+
+//--------------------------------------------------------------------------
+// Function:	Group overload constructor - dereference
+///\brief	Given a reference, ref, to an hdf5 group, creates a Group object
+///\param	attr - IN: Specifying location where the referenced object is in
+///\param	ref - IN: Reference pointer
+///\param	ref_type - IN: Reference type - default to H5R_OBJECT
+///\exception	H5::ReferenceException
+// Programmer	Binh-Minh Ribler - Oct, 2006
+//--------------------------------------------------------------------------
+Group::Group(Attribute& attr, void* ref, H5R_type_t ref_type) : H5Object()
+{
+    try {
+	id = p_dereference(attr.getId(), ref, ref_type);
+    } catch (ReferenceException deref_error) {
+	throw ReferenceException("Group constructor - located by an Attribute",
+		deref_error.getDetailMsg());
+    }
 }
 
 //--------------------------------------------------------------------------
@@ -204,8 +245,10 @@ void Group::close()
 	{
 	    throw GroupIException("Group::close", "H5Gclose failed");
 	}
-	// reset the id because the group that it represents is now closed
-	id = 0;
+	// reset the id when the group that it represents is no longer
+	// referenced
+	if (getCounter() == 0)
+	    id = 0;
     }
 }
 
diff --git a/c++/src/H5Group.h b/c++/src/H5Group.h
index 2c4fd10..c3641af 100644
--- a/c++/src/H5Group.h
+++ b/c++/src/H5Group.h
@@ -43,7 +43,8 @@ class H5_DLLCPP Group : public H5Object, public CommonFG {
 
 	// Creates a group by way of dereference.
 	Group(H5Object& obj, void* ref, H5R_type_t ref_type = H5R_OBJECT);
-	Group(H5File& obj, void* ref, H5R_type_t ref_type = H5R_OBJECT);
+	Group(H5File& h5file, void* ref, H5R_type_t ref_type = H5R_OBJECT);
+	Group(Attribute& attr, void* ref, H5R_type_t ref_type = H5R_OBJECT);
 
 	// default constructor
 	Group();
diff --git a/c++/src/H5IdComponent.cpp b/c++/src/H5IdComponent.cpp
index 0fb744f..e152d23 100644
--- a/c++/src/H5IdComponent.cpp
+++ b/c++/src/H5IdComponent.cpp
@@ -291,26 +291,6 @@ H5std_string IdComponent::p_get_file_name() const
 }
 
 //--------------------------------------------------------------------------
-// Function:	IdComponent::p_dereference (protected)
-// Purpose	Opens the HDF5 object referenced.
-// Parameters
-//		ref - IN: Reference pointer
-// Exception	H5::IdComponentException
-// Programmer	Binh-Minh Ribler - Oct, 2006
-//--------------------------------------------------------------------------
-#if 0
-hid_t IdComponent::p_dereference(hid_t obj_id, void* ref) const
-{
-   hid_t temp_id = H5Rdereference(obj_id, H5R_OBJECT, ref);
-   if (temp_id < 0)
-   {
-      throw ReferenceException("", "H5Rdereference failed");
-   }
-   return(temp_id);
-}
-#endif
-
-//--------------------------------------------------------------------------
 // Function:	IdComponent::p_get_refobj_type (protected)
 // Purpose	Retrieves the type of object that an object reference points to.
 // Parameters
diff --git a/c++/src/H5IdComponent.h b/c++/src/H5IdComponent.h
index 3333f3a..ec86d11 100644
--- a/c++/src/H5IdComponent.h
+++ b/c++/src/H5IdComponent.h
@@ -74,9 +74,6 @@ class H5_DLLCPP IdComponent {
 	virtual ~IdComponent();
 
    protected:
- /* 	hid_t p_dereference(hid_t obj_id, void* ref) const;
-	hid_t p_dereference(void* ref) const {return 0;};
- */ 
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
 
 	// Default constructor.
@@ -85,6 +82,9 @@ class H5_DLLCPP IdComponent {
 	// Gets the name of the file, in which an HDF5 object belongs.
 	H5std_string p_get_file_name() const;
 
+	// Retrieves the type of object that an object reference points to.
+	H5G_obj_t p_get_refobj_type(void *ref, H5R_type_t ref_type) const;
+
 	// Verifies that the given id is valid.
 	static bool p_valid_id(const hid_t obj_id);
 
@@ -94,9 +94,6 @@ class H5_DLLCPP IdComponent {
 
 	// Opens the HDF5 object referenced.
 
-	// Retrieves the type of object that an object reference points to.
-	H5G_obj_t p_get_refobj_type(void *ref, H5R_type_t ref_type) const;
-
 #endif // DOXYGEN_SHOULD_SKIP_THIS
 
 }; // end class IdComponent
diff --git a/c++/src/H5Object.cpp b/c++/src/H5Object.cpp
index 73d473c..23eab96 100644
--- a/c++/src/H5Object.cpp
+++ b/c++/src/H5Object.cpp
@@ -59,7 +59,7 @@ extern "C" herr_t userAttrOpWrpr( hid_t loc_id, const char* attr_name, void* op_
 //		set it to a valid HDF5 id.
 // Programmer	Binh-Minh Ribler - 2000
 //--------------------------------------------------------------------------
-H5Object::H5Object() : IdComponent(0) {}
+H5Object::H5Object() : IdComponent() {}
 
 //--------------------------------------------------------------------------
 // Function:	H5Object overloaded constructor (protected)
@@ -68,7 +68,7 @@ H5Object::H5Object() : IdComponent(0) {}
 // Parameters	object_id - IN: Id of an existing HDF5 object
 // Programmer	Binh-Minh Ribler - 2000
 //--------------------------------------------------------------------------
-H5Object::H5Object( const hid_t object_id ) : IdComponent( object_id ) {}
+//H5Object::H5Object( const hid_t object_id ) : IdComponent(), id(object_id) {}
 
 #endif // DOXYGEN_SHOULD_SKIP_THIS
 
@@ -338,13 +338,13 @@ H5std_string H5Object::getFileName() const
 }
 
 //--------------------------------------------------------------------------
-// Function:    H5Object::p_reference (protected)
-// Purpose      Creates a reference to an HDF5 object or a dataset region.
+// Function:	H5Object::p_reference (protected)
+// Purpose	Creates a reference to an HDF5 object or a dataset region.
 // Parameters
-//              name - IN: Name of the object to be referenced
-//              dataspace - IN: Dataspace with selection
-//              ref_type - IN: Type of reference; default to \c H5R_DATASET_REGION
-// Exception    H5::IdComponentException
+//		name - IN: Name of the object to be referenced
+//		dataspace - IN: Dataspace with selection
+//		ref_type - IN: Type of reference; default to \c H5R_DATASET_REGION
+// Exception    H5::ReferenceException
 // Programmer   Binh-Minh Ribler - May, 2004
 //--------------------------------------------------------------------------
 void H5Object::p_reference(void* ref, const char* name, hid_t space_id, H5R_type_t ref_type) const
@@ -352,20 +352,20 @@ void H5Object::p_reference(void* ref, const char* name, hid_t space_id, H5R_type
    herr_t ret_value = H5Rcreate(ref, getId(), name, ref_type, space_id);
    if (ret_value < 0)
    {
-      throw IdComponentException("", "H5Rcreate failed");
+      throw ReferenceException("", "H5Rcreate failed");
    }
 }
 
 //--------------------------------------------------------------------------
-// Function:    H5Object::reference
+// Function:	H5Object::reference
 ///\brief       Creates a reference to an HDF5 object or a dataset region.
 ///\param       ref - IN: Reference pointer
 ///\param       name - IN: Name of the object to be referenced
 ///\param       dataspace - IN: Dataspace with selection
 ///\param       ref_type - IN: Type of reference to query, valid values are:
-///             \li \c H5R_OBJECT \tReference is an object reference.
-///             \li \c H5R_DATASET_REGION \tReference is a dataset region
-///                     reference. - this is the default
+///		\li \c H5R_OBJECT \tReference is an object reference.
+///		\li \c H5R_DATASET_REGION \tReference is a dataset region
+///			reference. - this is the default
 ///\exception   H5::IdComponentException
 // Programmer   Binh-Minh Ribler - May, 2004
 //--------------------------------------------------------------------------
@@ -374,43 +374,63 @@ void H5Object::reference(void* ref, const char* name, const DataSpace& dataspace
    try {
       p_reference(ref, name, dataspace.getId(), ref_type);
    }
-   catch (IdComponentException E) {
-      throw IdComponentException("H5Object::reference", E.getDetailMsg());
+   catch (ReferenceException E) {
+      throw ReferenceException("H5Object::reference - dataset region", E.getDetailMsg());
    }
 }
 
 //--------------------------------------------------------------------------
-// Function:    H5Object::reference
-///\brief       This is an overloaded function, provided for your convenience.
-///             It differs from the above function in that it only creates
-///             a reference to an HDF5 object, not to a dataset region.
+// Function:	H5Object::reference
+///\brief	This is an overloaded function, provided for your convenience.
+///		It differs from the above function in that it takes an
+///		\c H5std_string for the object's name.
 ///\param       ref - IN: Reference pointer
-///\param       name - IN: Name of the object to be referenced - \c char pointer
+///\param       name - IN: Name of the object to be referenced
+///\param       dataspace - IN: Dataspace with selection
+///\param       ref_type - IN: Type of reference to query, valid values are:
+///		\li \c H5R_OBJECT \tReference is an object reference.
+///		\li \c H5R_DATASET_REGION \tReference is a dataset region
+///			reference. - this is the default
 ///\exception   H5::IdComponentException
-///\par Description
-//              This function passes H5R_OBJECT and -1 to the protected
-//              function for it to pass to the C API H5Rcreate
-//              to create a reference to the named object.
 // Programmer   Binh-Minh Ribler - May, 2004
 //--------------------------------------------------------------------------
+void H5Object::reference(void* ref, const H5std_string& name, const DataSpace& dataspace, H5R_type_t ref_type) const
+{
+    reference(ref, name.c_str(), dataspace, ref_type);
+}
+
+//--------------------------------------------------------------------------
+// Function:	H5Object::reference
+///\brief       This is an overloaded function, provided for your convenience.
+///		It differs from the above function in that it only creates
+///		a reference to an HDF5 object, not to a dataset region.
+///\param	ref - IN: Reference pointer
+///\param	name - IN: Name of the object to be referenced - \c char pointer
+///\exception	H5::IdComponentException
+///\par Description
+//		This function passes H5R_OBJECT and -1 to the protected
+//		function for it to pass to the C API H5Rcreate
+//		to create a reference to the named object.
+// Programmer	Binh-Minh Ribler - May, 2004
+//--------------------------------------------------------------------------
 void H5Object::reference(void* ref, const char* name) const
 {
    try {
       p_reference(ref, name, -1, H5R_OBJECT);
    }
-   catch (IdComponentException E) {
-      throw IdComponentException("H5Object::reference", E.getDetailMsg());
+   catch (ReferenceException E) {
+      throw ReferenceException("H5Object::reference - HDF5 object", E.getDetailMsg());
    }
 }
 
 //--------------------------------------------------------------------------
-// Function:    H5Object::reference
-///\brief       This is an overloaded function, provided for your convenience.
-///             It differs from the above function in that it takes an
-///             \c H5std_string for the object's name.
-///\param       ref - IN: Reference pointer
-///\param       name - IN: Name of the object to be referenced - \c H5std_string
-// Programmer   Binh-Minh Ribler - May, 2004
+// Function:	H5Object::reference
+///\brief	This is an overloaded function, provided for your convenience.
+///		It differs from the above function in that it takes an
+///		\c H5std_string for the object's name.
+///\param	ref - IN: Reference pointer
+///\param	name - IN: Name of the object to be referenced - \c H5std_string
+// Programmer	Binh-Minh Ribler - May, 2004
 //--------------------------------------------------------------------------
 void H5Object::reference(void* ref, const H5std_string& name) const
 {
@@ -418,39 +438,101 @@ void H5Object::reference(void* ref, const H5std_string& name) const
 }
 
 //--------------------------------------------------------------------------
-// Function:    H5Object::dereference
-// Purpose      Dereference a ref into an hdf5 object.
+// Function:	H5Object::p_dereference (protected)
+// Purpose	Dereference a ref into an hdf5 object.
 // Parameters
-//              ref - IN: Reference pointer
-// Exception    H5::IdComponentException
-// Programmer   Binh-Minh Ribler - Oct, 2006
+//		loc_id - IN: An hdf5 identifier specifying the location of the 
+//			 referenced object
+//		ref - IN: Reference pointer
+//		ref_type - IN: Reference type
+// Exception	H5::ReferenceException
+// Programmer	Binh-Minh Ribler - Oct, 2006
 // Modification
 //	May 2008 - BMR
-//		Moved from IdComponent into H5File and H5Object
+//		Moved from IdComponent.
 //--------------------------------------------------------------------------
-void H5Object::dereference(H5Object& obj, void* ref, H5R_type_t ref_type)
+hid_t H5Object::p_dereference(hid_t loc_id, void* ref, H5R_type_t ref_type)
 {
    hid_t temp_id;
-   temp_id = H5Rdereference(obj.getId(), ref_type, ref);
+   temp_id = H5Rdereference(loc_id, ref_type, ref);
    if (temp_id < 0)
    {
-      throw (inMemFunc("dereference"), "H5Rdereference failed");
+      throw ReferenceException("", "H5Rdereference failed");
    }
 
    // No failure, set id to the object
+   return(temp_id);
+}
+
+//--------------------------------------------------------------------------
+// Function:	H5Object::dereference
+///\brief	Dereferences a reference into an HDF5 object, given an HDF5 object.
+///\param	obj - IN: Object specifying the location of the referenced object
+///\param	ref - IN: Reference pointer
+///\param	ref_type - IN: Reference type
+///\exception	H5::ReferenceException
+// Programmer   Binh-Minh Ribler - Oct, 2006
+// Modification
+//	May, 2008
+//		Corrected missing parameters. - BMR
+//--------------------------------------------------------------------------
+void H5Object::dereference(H5Object& obj, void* ref, H5R_type_t ref_type)
+{
+   hid_t temp_id;
+   try {
+      temp_id = p_dereference(obj.getId(), ref, ref_type);
+   }
+   catch (ReferenceException E) {
+      throw ReferenceException("H5Object::dereference - located by object", E.getDetailMsg());
+   }
    p_setId(temp_id);
 }
 
+//--------------------------------------------------------------------------
+// Function:	H5Object::dereference
+///\brief	Dereferences a reference into an HDF5 object, given an HDF5 file.
+///\param	h5file - IN: HDF5 file specifying the location of the referenced object
+///\param	ref - IN: Reference pointer
+///\param	ref_type - IN: Reference type
+///\exception	H5::ReferenceException
+// Programmer   Binh-Minh Ribler - Oct, 2006
+// Modification
+//	May, 2008
+//		Corrected missing parameters. - BMR
+//--------------------------------------------------------------------------
 void H5Object::dereference(H5File& h5file, void* ref, H5R_type_t ref_type)
 {
    hid_t temp_id;
-   temp_id = H5Rdereference(h5file.getId(), ref_type, ref);
-   if (temp_id < 0)
-   {
-      throw (inMemFunc("dereference"), "H5Rdereference failed");
+   try {
+      temp_id = p_dereference(h5file.getId(), ref, ref_type);
+   }
+   catch (ReferenceException E) {
+      throw ReferenceException("H5Object::dereference - located by file", E.getDetailMsg());
    }
+   p_setId(temp_id);
+}
 
-   // No failure, set id to the object
+//--------------------------------------------------------------------------
+// Function:	H5Object::dereference
+///\brief	Dereferences a reference into an HDF5 object, given an attribute.
+///\param	attr - IN: Attribute specifying the location of the referenced object
+///\param	ref - IN: Reference pointer
+///\param	ref_type - IN: Reference type
+///\exception	H5::ReferenceException
+// Programmer   Binh-Minh Ribler - Oct, 2006
+// Modification
+//	May, 2008
+//		Corrected missing parameters. - BMR
+//--------------------------------------------------------------------------
+void H5Object::dereference(Attribute& attr, void* ref, H5R_type_t ref_type)
+{
+   hid_t temp_id;
+   try {
+      temp_id = p_dereference(attr.getId(), ref, ref_type);
+   }
+   catch (ReferenceException E) {
+      throw ReferenceException("H5Object::dereference - located by attribute", E.getDetailMsg());
+   }
    p_setId(temp_id);
 }
 
@@ -515,12 +597,12 @@ H5G_obj_t H5Object::p_get_refobj_type(void *ref, H5R_type_t ref_type) const
 #endif
 
 //--------------------------------------------------------------------------
-// Function:    H5Object::p_get_region (protected)
-// Purpose      Retrieves a dataspace with the region pointed to selected.
+// Function:	H5Object::p_get_region (protected)
+// Purpose	Retrieves a dataspace with the region pointed to selected.
 // Parameters
-//              ref_type - IN: Type of reference to get region of - default
-//                              to H5R_DATASET_REGION
-//              ref      - IN: Reference to get region of
+//		ref_type - IN: Type of reference to get region of - default
+//			to H5R_DATASET_REGION
+//		ref      - IN: Reference to get region of
 // Return       Dataspace id
 // Exception    H5::IdComponentException
 // Programmer   Binh-Minh Ribler - May, 2004
diff --git a/c++/src/H5Object.h b/c++/src/H5Object.h
index 1b1f656..ecaf41a 100644
--- a/c++/src/H5Object.h
+++ b/c++/src/H5Object.h
@@ -83,16 +83,20 @@ class H5_DLLCPP H5Object : public IdComponent {
 	void renameAttr(const char* oldname, const char* newname) const;
 	void renameAttr(const H5std_string& oldname, const H5std_string& newname) const;
 
-	// Creates a reference to a named Hdf5 object or to a dataset region
-	// in this object.
+	// Creates a reference to a dataset region in this object.
 	void reference(void* ref, const char* name, const DataSpace& dataspace,
-			H5R_type_t ref_type = H5R_DATASET_REGION) const;
+		H5R_type_t ref_type = H5R_DATASET_REGION) const;
+	void reference(void* ref, const H5std_string& name, const DataSpace& 
+		dataspace, H5R_type_t ref_type = H5R_DATASET_REGION) const;
+
+	// Creates a reference to a named HDF5 object.
 	void reference(void* ref, const char* name) const;
 	void reference(void* ref, const H5std_string& name) const;
 
 	// Open a referenced HDF5 object.
 	void dereference(H5File& h5file, void* ref, H5R_type_t ref_type = H5R_OBJECT);
 	void dereference(H5Object& obj, void* ref, H5R_type_t ref_type = H5R_OBJECT);
+        void dereference(Attribute& attr, void* ref, H5R_type_t ref_type = H5R_OBJECT);
 
 	// Copy constructor: makes copy of an H5Object object.
 	H5Object(const H5Object& original);
@@ -105,17 +109,17 @@ class H5_DLLCPP H5Object : public IdComponent {
 	// Default constructor
 	H5Object();
 
-	// Creates a copy of an existing object giving the object id
-	H5Object( const hid_t object_id );
-
 	// Gets the id of the H5 file in which the given object is located.
 	hid_t p_get_file_id();
 
 	// Creates a reference to an HDF5 object or a dataset region.
 	void p_reference(void* ref, const char* name, hid_t space_id, H5R_type_t ref_type) const;
 
+	// Dereferences a ref into an hdf5 object.
+	hid_t p_dereference(hid_t loc_id, void* ref, H5R_type_t ref_type);
+
 	// Retrieves the type of object that an object reference points to.
-	//H5G_obj_t p_get_refobj_type(void *ref, H5R_type_t ref_type) const;
+//	H5G_obj_t p_get_refobj_type(void *ref, H5R_type_t ref_type) const;
 
 	// Retrieves a dataspace with the region pointed to selected.
 	hid_t p_get_region(void *ref, H5R_type_t ref_type) const;
diff --git a/c++/src/H5PropList.cpp b/c++/src/H5PropList.cpp
index 14987f3..9fa031d 100644
--- a/c++/src/H5PropList.cpp
+++ b/c++/src/H5PropList.cpp
@@ -263,8 +263,10 @@ void PropList::close()
 	{
 	    throw PropListIException(inMemFunc("close"), "H5Pclose failed");
 	}
-	// reset the id because the property list that it represents is now closed
-	id = 0;
+	// reset the id when the property list that it represents is no longer
+	// referenced
+	if (getCounter() == 0)
+	    id = 0;
     }
 }