Changed semantic of Iptcdatum::setValue(const std::string&) !!! - it now creates a

value of a type determined by the Iptcdatum.
Added IptcData::op[] and Iptcdatum::op=. With this, you can do things like: 
iptcData["Iptc.Envelope.TimeSent"] = "14:41:0-05:00"; which creates a TimeValue.

src/iptc.cpp

@@ -81,6 +81,21 @@ namespace Exiv2 {
         return *this;
     } // Iptcdatum::operator=
     
+    Iptcdatum& Iptcdatum::operator=(const uint16_t& value)
+    {
+        UShortValue::AutoPtr v = UShortValue::AutoPtr(new UShortValue);
+        v->value_.push_back(value);
+        value_ = v;
+        modified_ = true;
+        return *this;
+    }
+
+    Iptcdatum& Iptcdatum::operator=(const std::string& value)
+    {
+        setValue(value);
+        return *this;
+    }
+
     void Iptcdatum::setValue(const Value* pValue)
     {
         modified_ = true;
@@ -90,9 +105,18 @@ namespace Exiv2 {
 
     void Iptcdatum::setValue(const std::string& buf)
     {
+        Value::AutoPtr value;
+        try {
+            TypeId type = IptcDataSets::dataSetType(tag(), record());
+            value = Value::create(type);
+        }
+        catch (const Error&) {
+            // Default to a StringValue if the type is unknown or the parse fails
+            value = Value::create(string);
+        }
+        value->read(buf);
+        value_ = value;
         modified_ = true;
-        if (value_.get() == 0) value_ = Value::create(string);
-        value_->read(buf);
     }
 
     const byte IptcData::marker_ = 0x1C;          // Dataset marker
@@ -107,6 +131,17 @@ namespace Exiv2 {
         delete[] pData_;
     }
 
+    Iptcdatum& IptcData::operator[](const std::string& key)
+    {
+        IptcKey iptcKey(key);
+        iterator pos = findKey(iptcKey);
+        if (pos == end()) {
+            add(Iptcdatum(iptcKey));
+            pos = findKey(iptcKey);
+        }
+        return *pos;
+    }
+
     int IptcData::read(const std::string& path)
     {
         if (!fileExists(path, true)) return -1;

src/iptc.hpp

@@ -79,15 +79,27 @@ namespace Exiv2 {
         //@{
         //! Assignment operator
         Iptcdatum& operator=(const Iptcdatum& rhs);
+        /*!
+          @brief Assign \em value to the %Iptcdatum. The type of the new value
+                 is determined from %Iptcdatum. If that fails, a StringValue is
+                 used. Calls setValue(const std::string&).
+         */
+        Iptcdatum& operator=(const std::string& value);
+        /*!
+          @brief Assign \em value to the %Iptcdatum. The type of the new value
+                 is set to UShortValue.
+         */
+        Iptcdatum& operator=(const uint16_t& value);
         /*!
           @brief Set the value. This method copies (clones) the value pointed
                  to by pValue.
          */
         void setValue(const Value* pValue);
         /*!
-          @brief Set the value to the string buf. 
-                 Uses Value::read(const std::string& buf). If the Iptcdatum does
-                 not have a value yet, then an StringValue is created.
+          @brief Set the value to the string buf. Uses Value::read(const
+                 std::string& buf). If the %Iptcdatum does not have a value yet,
+                 then a value of the correct type for this %Iptcdatum is
+                 created. If that fails, a StringValue is created.
          */
         void setValue(const std::string& buf);
         //@}
@@ -342,6 +354,15 @@ namespace Exiv2 {
           @return Data buffer containing the Iptc data.
          */
         DataBuf copy();
+        /*!
+          @brief Returns a reference to the %Iptcdatum that is associated with a
+                 particular \em key. If %IptcData does not already contain such
+                 an %Iptcdatum, operator[] adds object \em Iptcdatum(key).
+
+          @note  Since operator[] might insert a new element, it can't be a const
+                 member function.
+         */
+        Iptcdatum& operator[](const std::string& key);
         /*!
           @brief Add an %Iptcdatum from the supplied key and value pair. This
                  method copies (clones) the value. A check for non-repeatable