Add some documentation

    * include/dynamic-graph/command-getter.h,
    * include/dynamic-graph/command-setter.h,
    * include/dynamic-graph/command.h.

include/dynamic-graph/command-getter.h

@@ -26,6 +26,32 @@ namespace dynamicgraph {
     ///
     /// Command that calls a parameter getter function
     ///
+    /// This class is templated by a type E deriving from entity and
+    /// a type T of data.
+    ///
+    /// Let us assume that class E has a private member of type T and a
+    /// public getter function for this member:
+    /// \code
+    /// class E : public Entity
+    /// {
+    /// public:
+    ///   E (const std::string& inName) : Entity(inName) {}
+    ///   T getParameter() const {return parameter_;}
+    /// private:
+    ///   T parameter_;
+    /// };
+    /// \endcode
+    /// Then the command defined by:
+    /// \code
+    /// E entity("MyEntity");
+    /// Getter<E,T> command(entity, &E::getParameter)
+    /// \endcode
+    /// returns the value of <c>entity.parameter_</c> upon invocation.
+    ///
+    /// \note
+    /// \li T should be a type supported by class Value,
+    /// \li prototype of E::getParameter should be exactly as specified in this
+    /// example.
     template <class E, typename T>
     class Getter : public Command {
     public:
@@ -33,7 +59,7 @@ namespace dynamicgraph {
       typedef T (E::*GetterMethod) () const;
       /// Constructor
       Getter(E& entity, GetterMethod);
-      
+
     protected:
       virtual Value doExecute();
 

include/dynamic-graph/command-setter.h

@@ -26,6 +26,32 @@ namespace dynamicgraph {
     ///
     /// Command that calls a parameter setter function
     ///
+    /// This class is templated by a type E deriving from entity and
+    /// a type T of data.
+    ///
+    /// Let us assume that class E has a private member of type T and a
+    /// public setter function for this member:
+    /// \code
+    /// class E : public Entity
+    /// {
+    /// public:
+    ///   E (const std::string& inName) : Entity(inName) {}
+    ///   void setParameter(const T& parameter) {parameter_ = parameter;}
+    /// private:
+    ///   T parameter_;
+    /// };
+    /// \endcode
+    /// Then the command defined by:
+    /// \code
+    /// E entity("MyEntity");
+    /// Setter<E,T> command(entity, &E::getParameter)
+    /// \endcode
+    /// sets the value of <c>entity.parameter_</c> upon invocation.
+    ///
+    /// \note
+    /// \li T should be a type supported by class Value,
+    /// \li prototype of E::setParameter should be exactly as specified in this
+    /// example.
     template <class E, typename T>
     class Setter : public Command {
     public:
@@ -33,7 +59,7 @@ namespace dynamicgraph {
       typedef void (E::*SetterMethod) (const T&);
       /// Constructor
       Setter(E& entity, SetterMethod);
-      
+
     protected:
       virtual Value doExecute();
 

include/dynamic-graph/command.h

@@ -28,9 +28,18 @@ namespace dynamicgraph {
     /// Abstract class for entity commands
     ///
     /// This class provide a mean to control entities from external python script.
-    /// A command has several parameters (dynamicgraph::parameter) that can take
-    /// various types of values (dynamicgraph::Value).
-
+    ///
+    /// A command
+    /// \li is owned by an entity,
+    /// \li takes parameters of type Value,
+    /// \li return an instance of Value when calling Command::execute()
+    ///
+    /// At construction, the prototype of the command is defined by providing
+    /// a vector of Value::Type.
+    ///
+    /// Parameters are set by calling Command::setParameterValues with a
+    /// vector of Values the types of which should fit the vector specified
+    /// at construction.
     class DYNAMICGRAPH_EXPORT Command
     {
     public: