diff --git a/src/factory/Compare.cpp b/src/factory/Compare.cpp
index fe443cc..6f2fd3c 100644
--- a/src/factory/Compare.cpp
+++ b/src/factory/Compare.cpp
@@ -271,7 +271,7 @@ bool compareField(const PVUnion* left, const PVUnion* right)
         
     if (ls->isVariant())
     {
-        PVFieldPtr lval = left->get();
+        const PVField::const_shared_pointer& lval = left->get();
         if (lval.get() == 0)
             return right->get().get() == 0;
         else
diff --git a/src/factory/FieldCreateFactory.cpp b/src/factory/FieldCreateFactory.cpp
index 1d20323..ca53544 100644
--- a/src/factory/FieldCreateFactory.cpp
+++ b/src/factory/FieldCreateFactory.cpp
@@ -611,6 +611,44 @@ Union::Union (
 
 Union::~Union() { }
 
+int32 Union::guess(Type t, ScalarType s) const
+{
+    if(t!=scalar && t!=scalarArray)
+        THROW_EXCEPTION2(std::logic_error, "PVUnion::guess() only support scalar and scalarArray");
+
+    int32 ret = -1;
+    for(size_t i=0, N=fields.size(); i<N; i++)
+    {
+        if(fields[i]->getType()!=t)
+            continue;
+
+        ScalarType type;
+        switch(fields[i]->getType()) {
+        case scalar:
+            type = static_cast<const Scalar*>(fields[i].get())->getScalarType();
+            break;
+        case scalarArray:
+            type = static_cast<const ScalarArray*>(fields[i].get())->getElementType();
+            break;
+        case structure:
+        case structureArray:
+        case union_:
+        case unionArray:
+            continue;
+        }
+
+        if(type==s) {
+            // exact match
+            ret = i;
+            break; // we're done
+
+        } else if(ret==-1) {
+            // first partial match
+            ret = i;
+        }
+    }
+    return ret;
+}
 
 string Union::getID() const
 {
diff --git a/src/factory/PVUnion.cpp b/src/factory/PVUnion.cpp
index bc6ae7c..5450dbe 100644
--- a/src/factory/PVUnion.cpp
+++ b/src/factory/PVUnion.cpp
@@ -40,24 +40,7 @@ PVUnion::PVUnion(UnionConstPtr const & unionPtr)
 
 #undef PVUNION_UNDEFINED_INDEX
 
-PVUnion::~PVUnion()
-{
-}
-
-UnionConstPtr PVUnion::getUnion() const
-{
-    return unionPtr;
-}
-
-PVFieldPtr PVUnion::get() const
-{
-    return value;
-}
-
-int32 PVUnion::getSelectedIndex() const
-{
-    return selector;
-}
+PVUnion::~PVUnion() {}
 
 string PVUnion::getSelectedFieldName() const
 {
@@ -100,11 +83,6 @@ PVFieldPtr PVUnion::select(string const & fieldName)
         throw std::invalid_argument("no such fieldName");
 	return select(index);
 }
-	
-void PVUnion::set(PVFieldPtr const & value)
-{
-    set(selector, value);
-}
 
 void PVUnion::set(int32 index, PVFieldPtr const & value)
 {
@@ -203,7 +181,7 @@ std::ostream& PVUnion::dumpValue(std::ostream& o) const
     o << format::indent() << getUnion()->getID() << ' ' << getFieldName() << std::endl;
     {
     	format::indent_scope s(o);
-		PVFieldPtr fieldField = get();
+        const PVField::const_shared_pointer& fieldField = get();
 		if (fieldField.get() == NULL)
 		  o << format::indent() << "(none)" << std::endl;
 		else
@@ -232,7 +210,7 @@ void PVUnion::copy(const PVUnion& from)
 void PVUnion::copyUnchecked(const PVUnion& from)
 {
 
-    PVFieldPtr fromValue = from.get();
+    const PVField::const_shared_pointer& fromValue = from.get();
     if (from.getUnion()->isVariant())
     {
         if (fromValue.get() == 0)
diff --git a/src/json/print.cpp b/src/json/print.cpp
index 1a9f450..e834473 100644
--- a/src/json/print.cpp
+++ b/src/json/print.cpp
@@ -130,7 +130,7 @@ void show_field(args& A, const pvd::PVField* fld)
     case pvd::union_:
     {
         const pvd::PVUnion *U=static_cast<const pvd::PVUnion*>(fld);
-        pvd::PVFieldPtr C(U->get());
+        const pvd::PVField::const_shared_pointer& C(U->get());
 
         if(!C) {
             A.strm<<"null";
diff --git a/src/pv/pvData.h b/src/pv/pvData.h
index 37e1e03..adc5ea3 100644
--- a/src/pv/pvData.h
+++ b/src/pv/pvData.h
@@ -959,19 +959,25 @@ public:
      * Get the introspection interface
      * @return The interface.
      */
-    UnionConstPtr getUnion() const;
+    inline const UnionConstPtr& getUnion() const { return unionPtr; }
 
     /**
      * Get the @c PVField value stored in the field.
      * @return @c PVField value of field, @c null if {@code getSelectedIndex() == UNDEFINED_INDEX}.
      */
-    PVFieldPtr get() const;
+    inline const PVFieldPtr& get() { return value; }
+    inline PVField::const_shared_pointer get() const { return value; }
    
     template<typename PVT>
-    std::tr1::shared_ptr<PVT> get() const {
+    inline std::tr1::shared_ptr<PVT> get() {
         return std::tr1::dynamic_pointer_cast<PVT>(get());
     }
-        
+
+    template<typename PVT>
+    inline std::tr1::shared_ptr<const PVT> get() const {
+        return std::tr1::dynamic_pointer_cast<const PVT>(get());
+    }
+
     /**
      * Select field (set index) and get the field at the index.
      * @param index index of the field to select.
@@ -981,7 +987,7 @@ public:
     PVFieldPtr select(int32 index);
 
     template<typename PVT>
-    std::tr1::shared_ptr<PVT> select(int32 index) {
+    inline std::tr1::shared_ptr<PVT> select(int32 index) {
         return std::tr1::dynamic_pointer_cast<PVT>(select(index));
     }
 
@@ -994,7 +1000,7 @@ public:
     PVFieldPtr select(std::string const & fieldName);
 
     template<typename PVT>
-    std::tr1::shared_ptr<PVT> select(std::string const & fieldName) {
+    inline std::tr1::shared_ptr<PVT> select(std::string const & fieldName) {
         return std::tr1::dynamic_pointer_cast<PVT>(select(fieldName));
     }
 
@@ -1002,21 +1008,23 @@ public:
      * Get selected field index.
      * @return selected field index.
      */
-    int32 getSelectedIndex() const;
+    inline int32 getSelectedIndex() const { return selector; }
     
     /**
      * Get selected field name.
      * @return selected field name, empty string if field does not exist.
      */
     std::string getSelectedFieldName() const;
-    
+
     /**
      * Set the @c PVField (by reference!) as selected field.
      * If a value is not a valid union field an @c std::invalid_argument
      * exception is thrown.
      * @param value the field to set.
      */
-    void set(PVFieldPtr const & value);
+    inline void set(PVFieldPtr const & value) {
+        set(selector, value);
+    }
     /**
      * Set the @c PVField (by reference!) as field at given index.
      * If a value is not a valid union field an @c std::invalid_argument
@@ -1027,6 +1035,7 @@ public:
      * @see #select(int32)
      */
     void set(int32 index, PVFieldPtr const & value);
+
     /**
      * Set the @c PVField (by reference!) as field by given name.
      * If a value is not a valid union field an @c std::invalid_argument
@@ -1067,7 +1076,7 @@ private:
     static PVDataCreatePtr pvDataCreate;
 
     friend class PVDataCreate;
-    UnionConstPtr unionPtr;
+    UnionConstPtr unionPtr; // same as PVField::getField()
 
 	int32 selector;
 	PVFieldPtr value;
diff --git a/src/pv/pvIntrospect.h b/src/pv/pvIntrospect.h
index be57a6e..36f92fd 100644
--- a/src/pv/pvIntrospect.h
+++ b/src/pv/pvIntrospect.h
@@ -856,6 +856,17 @@ public:
      */
     bool isVariant() const {return (fieldNames.size() == 0);}
 
+    /** Attempt to find an suitable member to stored the specified type.
+     *
+     * Returned index is guerenteed to by of specified Type (either scalar or scalarArray).
+     * Provided ScalarType is taken as a hint.
+     *
+     @param t Must be either scalar or scalarArray
+     @param s The preferred ScalarType
+     @returns A valid index or -1
+     */
+    int32 guess(Type t, ScalarType s) const;
+
     virtual std::string getID() const;
 
     virtual std::ostream& dump(std::ostream& o) const;