Unify the shiboken sample binding example description

Merge the description from the shiboken documentation into the newly
added example samplebinding.rst file, re-using the
existing image.
Add the sections from the shiboken documentation to the source
files via .rstinc files.

Task-number: PYSIDE-1106
Pick-to: 6.5
Change-Id: I22f7302aa10ce2a47283b01315b2d4c9daf9f9ed
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>

4 files changed, 50 insertions, 2 deletions

diff --git a/examples/samplebinding/doc/bindings.h.rstinc b/examples/samplebinding/doc/bindings.h.rstinc
new file mode 100644
index 000000000..e2a0b6fef
--- /dev/null
+++ b/examples/samplebinding/doc/bindings.h.rstinc
@@ -0,0 +1,2 @@
+The Shiboken generator needs a header file that includes
+the types we are interested in:
diff --git a/examples/samplebinding/doc/bindings.xml.rstinc b/examples/samplebinding/doc/bindings.xml.rstinc
new file mode 100644
index 000000000..8d078ce7f
--- /dev/null
+++ b/examples/samplebinding/doc/bindings.xml.rstinc
@@ -0,0 +1,32 @@
+Shiboken requires an XML-based typesystem file that defines the
+relationship between C++ and Python types.
+
+It declares the two aforementioned classes. One of them as an
+“object-type” and the other as a “value-type”. The main difference is that
+object-types are passed around in generated code as pointers, whereas
+value-types are copied (value semantics).
+
+By specifying the names of these classes in the typesystem file, Shiboken
+automatically tries to generate bindings for all methods of those
+classes. You need not mention all the methods manually in the XML file, unless
+you want to modify them.
+
+Object ownership rules
+----------------------
+
+Shiboken doesn't know if Python or C++ are responsible for freeing the C++
+objects that were allocated in the Python code, and assuming this might lead to
+errors. There can be cases where Python should release the C++ memory when the
+reference count of the Python object becomes zero, but it should never delete
+the underlying C++ object just from assuming that it will not be deleted by
+underlying C++ library, or if it's maybe parented to another object (like
+QWidgets).
+
+In our case, the :code:`clone()` method is only called inside the C++ library,
+and we assume that the C++ code takes care of releasing the cloned object.
+
+As for :code:`addIcecreamFlavor()`, we know that a :code:`Truck` owns the
+:code:`Icecream` object, and will remove it once the :code:`Truck` is
+destroyed. That's why the ownership is set to “c++” in the typesystem file,
+so that the C++ objects are not deleted when the corresponding Python names
+go out of scope.
diff --git a/examples/samplebinding/doc/samplebinding.pyproject b/examples/samplebinding/doc/samplebinding.pyproject
index 82c485a09..b0786355f 100644
--- a/examples/samplebinding/doc/samplebinding.pyproject
+++ b/examples/samplebinding/doc/samplebinding.pyproject
@@ -1,5 +1,6 @@
 {
     "files": ["../bindings.h",
+              "../bindings.xml",
               "../icecream.cpp",
               "../icecream.h",
               "../macros.h",
diff --git a/examples/samplebinding/doc/samplebinding.rst b/examples/samplebinding/doc/samplebinding.rst
index 8d74be281..e96e99df4 100644
--- a/examples/samplebinding/doc/samplebinding.rst
+++ b/examples/samplebinding/doc/samplebinding.rst
@@ -54,8 +54,8 @@ done by specifying a special XML file called a typesystem file.
 
 In the typesystem file you specify things like:
 
- * which C++ classes should have bindings (Icecream) and what kind of
-   semantics (value / object)
+ * Which C++ classes should have bindings (Icecream, Truck) and with what
+   kind of semantics (value / object)
 
  * Ownership rules (who deletes the C++ objects, C++ or Python)
 
@@ -186,12 +186,25 @@ On Windows:
     ninja install
     cd ..
 
+Use the Python module
++++++++++++++++++++++
+
 The final example can then be run by:
 
 .. code-block:: bash
 
     python main.py
 
+In the ``main.py`` script, two types are derived from :code:`Icecream` for
+different “flavors” after importing the classes from the :code:`Universe`
+module. Then, a :code:`truck` is created to deliver some regular flavored
+Icecreams and two special ones.
+
+If the delivery fails, a new :code:`truck` is created with the old flavors
+copied over, and a new *magical* flavor that will surely satisfy all customers.
+
+Try running it to see if the ice creams are delivered.
+
 Windows troubleshooting
 +++++++++++++++++++++++