From 4a7609fa741e54610b27c6a30d6a9543e19f4031 Mon Sep 17 00:00:00 2001
From: Jitse Niesen <jitse@maths.leeds.ac.uk>
Date: Thu, 5 Jul 2012 13:36:02 +0100
Subject: [PATCH] doc: Add constructor to example for inheritance. See "Error
 in Inheriting Eigen::Vector3d" on forum. (transplanted from
 b582b2ebdc5657c993698e89db699e885af68c55 )

---
 doc/I00_CustomizingEigen.dox | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/doc/I00_CustomizingEigen.dox b/doc/I00_CustomizingEigen.dox
index 623ef31e1..43ac8509a 100644
--- a/doc/I00_CustomizingEigen.dox
+++ b/doc/I00_CustomizingEigen.dox
@@ -83,7 +83,7 @@ An example of when you actually need to inherit Matrix, is when you have
 several layers of heritage such as  MyVerySpecificVector1,MyVerySpecificVector1 -> MyVector1 -> Matrix and.
 MyVerySpecificVector3,MyVerySpecificVector4 -> MyVector2 -> Matrix.
 
-In order for your object to work within the Eigen framework, you need to
+In order for your object to work within the %Eigen framework, you need to
 define a few members in your inherited class.
 
 Here is a minimalistic example:\n
@@ -93,8 +93,15 @@ class MyVectorType : public  Eigen::VectorXd
 public:
     MyVectorType(void):Eigen::VectorXd() {}
 
-    // You need to define this for your object to work
     typedef Eigen::VectorXd Base;
+
+    // This constructor allows you to construct MyVectorType from Eigen expressions
+    template<typename OtherDerived>
+    Vector3D(const Eigen::MatrixBase<OtherDerived>& other)
+        : Eigen::Vector3d(other)
+    { }
+
+    // This method allows you to assign Eigen expressions to MyVectorType
     template<typename OtherDerived>
     MyVectorType & operator= (const Eigen::MatrixBase <OtherDerived>& other)
     {