Re-ordered topics to better support feature dependencies

_config.yml

@@ -117,8 +117,9 @@ episode_order:
   - introduction
   - modules
   - derived_types
+  - extending_types
   - interfaces
   - type_bound_procedures
   - destructors
-  - type_extension
+#  - polymorphism
 

_episodes/destructors.md

@@ -22,7 +22,7 @@ module m_vector
     contains
     
     procedure:: display
-    final:: destructor
+    final:: destructor_vector
     
   end type
   
@@ -31,13 +31,33 @@ module m_vector
     procedure:: create_sized_vector
   end interface
   
+  type,extends(t_vector):: t_vector_3
+    
+    contains
+    
+    final:: destructor_vector_3
+    
+  end type
+  
+  interface t_vector_3
+    procedure:: create_size_3_vector
+  end interface
+  
   contains
   
-  subroutine destructor(self)
+  subroutine destructor_vector(self)
     implicit none
     type(t_vector):: self
     
-    print*, "t_vector destruction called"
+    if (allocated(self%elements)) then
+      deallocate(self%elements)
+    endif
+  end subroutine
+  
+  subroutine destructor_vector_3(self)
+    implicit none
+    type(t_vector_3):: self
+    
     if (allocated(self%elements)) then
       deallocate(self%elements)
     endif
@@ -48,9 +68,14 @@ module m_vector
     class(t_vector),intent(in):: vec
     integer:: i
     
-    print*, "t_vector:"
-    print*, "  num_elements=",vec%num_elements
-    print*, "  elements="
+    select type (vec)
+      class is (t_vector)
+        print*, "t_vector:"
+      class is (t_vector_3)
+        print*, "t_vector_3:"
+    end select
+    print*, " num_elements=",vec%num_elements
+    print*, " elements="
     do i=1,vec%num_elements
       print*, "  ",vec%elements(i)
     end do
@@ -68,20 +93,19 @@ module m_vector
     allocate(create_sized_vector%elements(vec_size))
   end function
   
-end module
-
-subroutine make_vector_in_different_scope()
-  use m_vector
-  type(t_vector) test
+  type(t_vector_3) function create_size_3_vector()
+    implicit none
+    create_size_3_vector%num_elements=3
+    allocate(create_size_3_vector%elements(3))
+  end function
   
-  test=t_vector(4)
-end subroutine
+end module
 
 program main
   use m_vector
   implicit none
-  integer:: temp
   type(t_vector) numbers_none,numbers_some
+  type(t_vector_3) location
   
   numbers_none=t_vector()
   call numbers_none%display()
@@ -90,12 +114,14 @@ program main
   numbers_some%elements(1)=2
   call numbers_some%display()
   
-  call make_vector_in_different_scope()
+  location=t_vector_3()
+  location%elements(1)=1.0
+  call location%display()
   
 end program
 ~~~
 {: .fortran}
-[destructors.f90](https://github.com/acenet-arc/fortran_oop_as_a_second_language/blob/gh-pages/code/destructors.f90)
+[destructor.f90](https://github.com/acenet-arc/fortran_oop_as_a_second_language/blob/gh-pages/code/destructor.f90)
 </div>
 
 {% include links.md %}

_episodes/extending_types.md

@@ -0,0 +1,72 @@
+---
+title: "Extended Types"
+teaching: 10
+exercises: 0
+questions:
+- "How do you extend a type?"
+objectives:
+- "Create an extend a type."
+keypoints:
+- "Type extension allows you to build upon an existing derived type to create a new derived type."
+---
+
+<div class="gitfile" markdown="1">
+~~~
+module m_vector
+  implicit none
+  
+  type t_vector
+    integer:: num_elements
+    real,dimension(:),allocatable:: elements
+  end type
+  
+  type,extends(t_vector):: t_vector_3
+  end type
+  
+  contains
+  
+  type(t_vector) function create_empty_vector()
+    implicit none
+    create_empty_vector%num_elements=0
+  end function
+  
+  type(t_vector) function create_sized_vector(vec_size)
+    implicit none
+    integer,intent(in):: vec_size
+    create_sized_vector%num_elements=vec_size
+    allocate(create_sized_vector%elements(vec_size))
+  end function
+  
+  type(t_vector_3) function create_size_3_vector()
+    implicit none
+    create_size_3_vector%num_elements=3
+    allocate(create_size_3_vector%elements(3))
+  end function
+  
+end module
+
+program main
+  use m_vector
+  implicit none
+  type(t_vector) numbers_none,numbers_some
+  type(t_vector_3) location
+  
+  numbers_none=create_empty_vector()
+  print*, "numbers_none%num_elements=",numbers_none%num_elements
+  
+  numbers_some=create_sized_vector(4)
+  numbers_some%elements(1)=2
+  print*, "numbers_some%num_elements=",numbers_some%num_elements
+  print*, "numbers_some%elements(1)=",numbers_some%elements(1)
+  
+  location=create_size_3_vector()
+  location%elements(1)=1.0
+  print*, "location%elements(1)=",location%elements(1)
+  
+end program
+~~~
+{: .fortran}
+[type_extension.f90](https://github.com/acenet-arc/fortran_oop_as_a_second_language/blob/gh-pages/code/type_extension.f90)
+</div>
+
+{% include links.md %}

_episodes/interfaces.md

@@ -26,6 +26,13 @@ module m_vector
     procedure:: create_sized_vector
   end interface
   
+  type,extends(t_vector):: t_vector_3
+  end type
+  
+  interface t_vector_3
+    procedure:: create_size_3_vector
+  end interface
+  
   contains
   
   type(t_vector) function create_empty_vector()
@@ -40,12 +47,19 @@ module m_vector
     allocate(create_sized_vector%elements(vec_size))
   end function
   
+  type(t_vector_3) function create_size_3_vector()
+    implicit none
+    create_size_3_vector%num_elements=3
+    allocate(create_size_3_vector%elements(3))
+  end function
+  
 end module
 
 program main
   use m_vector
   implicit none
   type(t_vector) numbers_none,numbers_some
+  type(t_vector_3) location
   
   numbers_none=t_vector()
   print*, "numbers_none%num_elements=",numbers_none%num_elements
@@ -55,15 +69,19 @@ program main
   print*, "numbers_some%num_elements=",numbers_some%num_elements
   print*, "numbers_some%elements(1)=",numbers_some%elements(1)
   
+  location=t_vector_3()
+  location%elements(1)=1.0
+  print*, "location%elements(1)=",location%elements(1)
+  
 end program
 ~~~
 {: .fortran}
-[intefrace_blocks.f90](https://github.com/acenet-arc/fortran_oop_as_a_second_language/blob/gh-pages/code/intefrace_blocks.f90)
+[interface_blocks.f90](https://github.com/acenet-arc/fortran_oop_as_a_second_language/blob/gh-pages/code/interface_blocks.f90)
 </div>
 
 This example uses what is called a generic interface which allows you to map a number of procedures to one name. The specific procedure is chosen based on the supplied arguments. Therefore each procedure included in the generic interface must be distinguishable by it number and type of arguments.
 
-The way this interface has been used to create a new object of a given derived type is pattern often reffered to as a constructor in object oriented programming languages.
+When the interface has been given a name that matches a type name it used to create it is commonly called a constructor, which is used to initialize the newly created object.
 
 {% include links.md %}
 

_episodes/introduction.md

@@ -9,7 +9,7 @@ objectives:
 keypoints:
 - "First key point. Brief Answer to questions. (FIXME)"
 ---
-FIXME
+A cool intro some more cool stuff
 
 {% include links.md %}