add Bader's draft about OOP in Fortran to the learning section

data/learning.yml

@@ -276,6 +276,16 @@ books:
       - link: /learn/intrinsics/UNPACK
       - link: /learn/intrinsics/VERIFY
 
+  - title: Fortran Object Oriented Programming
+    description: Putting Fortran’s object-related features to practical use
+    category: Fortran Documentation
+    link: /learn/oop_features_in_fortran
+    pages:
+      - /learn/oop_features_in_fortran
+      - /learn/oop_features_in_fortran/object_based_programming_techniques
+      - /learn/oop_features_in_fortran/object_oriented_programming_techniques
+      - /learn/oop_features_in_fortran/performance_and_ease_of_use
+
 # Web links listed at the bottom of the 'Learn' landing page
 #
 reference-links:

source/learn.md

@@ -185,4 +185,5 @@ learn/building_programs/index
 learn/best_practices/index
 learn/intrinsics/index
 learn/rosetta_stone
+learn/oop_features_in_fortran/index
 :::

source/learn/oop_features_in_fortran/index.md

@@ -0,0 +1,38 @@
+# Putting Fortran’s object-related features to practical use
+
+:::{toctree}
+:maxdepth: 2
+:hidden:
+Object-based programming techniques <object_based_programming_techniques>
+Object-oriented programming techniques <object_oriented_programming_techniques>
+Performance and ease of use <performance_and_ease_of_use>
+:::
+
+This article by the late Reinhold Bader (1966-2024)
+describes how advanced Fortran language features can be
+applied toward object-based and object-oriented programming techniques.
+These are, of course, to a significant extent a matter of taste,
+personal style and possibly overarching program design considerations,
+so should be taken with a pinch of salt.
+
+Language features from Fortran 95 and later will be used; those from
+Fortran 2003 and later will also be shortly described. They are
+explained in more detail in e.g., Metcalf, Reid, Cohen and Bader.[^mfe]
+See also [Fortran 95 language
+features](https://en.wikipedia.org/wiki/Fortran_95_language_features) for
+the language's fundamentals; the prerequisite for understanding this article
+is that features explained there are well understood.
+
+Boldface will be used where term definitions are introduced. They are
+additionally annotated by "(not a Fortran term)" or similar if the term
+is not used in the Fortran standard itself, but is in general use in the
+technical literature.
+
+Compilable and runnable example code is available from an external
+[Github repository](https://github.com/reinh-bader/object_fortran).
+
+[^mfe]:
+    Metcalf, Michael; Reid, John; Cohen, Malcolm; Bader, Reinhold (2023).
+    _Modern Fortran Explained._ Numerical Mathematics and Scientific Computation.
+    Oxford University Press.
+    [ISBN 978-0-19-887657-1](https://en.wikipedia.org/wiki/Special:BookSources/978-0-19-887657-1).