Add QPDFObjectHandle::getObjGen()

This is safer than getObjectID() and getGeneration() for many uses.

ChangeLog

@@ -1,5 +1,9 @@
 2013-06-14  Jay Berkenbilt  <ejb@ql.org>
 
+	* Add new QPDFObjectHandle::getObjGen() method and indiciate in
+	comments that its use is favored over getObjectID() and
+	getGeneration() for most cases.
+
 	* Add new QPDFObjGen object to represent an object ID/generation
 	pair.
 

include/qpdf/QPDFObjectHandle.hh

@@ -16,6 +16,7 @@
 #include <set>
 #include <map>
 
+#include <qpdf/QPDFObjGen.hh>
 #include <qpdf/PointerHolder.hh>
 #include <qpdf/Buffer.hh>
 #include <qpdf/InputSource.hh>
@@ -454,7 +455,17 @@ class QPDFObjectHandle
 			   QPDFObjectHandle const& filter,
 			   QPDFObjectHandle const& decode_parms);
 
-    // return 0 for direct objects
+    // Access object ID and generation.  For direct objects, return
+    // object ID 0.
+
+    // NOTE: Be careful about calling getObjectID() and
+    // getGeneration() directly as this can lead to the pattern of
+    // depending on object ID or generation without the other.  In
+    // general, when keeping track of object IDs, it's better to use
+    // QPDFObjGen instead.
+
+    QPDF_DLL
+    QPDFObjGen getObjGen() const;
     QPDF_DLL
     int getObjectID() const;
     QPDF_DLL

libqpdf/QPDFObjectHandle.cc

@@ -535,6 +535,12 @@ QPDFObjectHandle::replaceStreamData(PointerHolder<StreamDataProvider> provider,
 	provider, filter, decode_parms);
 }
 
+QPDFObjGen
+QPDFObjectHandle::getObjGen() const
+{
+    return QPDFObjGen(this->objid, this->generation);
+}
+
 int
 QPDFObjectHandle::getObjectID() const
 {