deprecated regionized pointers

doc/manual.rst

@@ -1507,68 +1507,6 @@ non nilable pointers. The details of this analysis are still to be specified
 here.
 
 
-Memory regions
---------------
-
-The types ``ref`` and ``ptr`` can get an optional ``region`` annotation.
-A region has to be an object type.
-
-Regions are very useful to separate user space and kernel memory in the
-development of OS kernels:
-
-.. code-block:: nim
-  type
-    Kernel = object
-    Userspace = object
-
-  var a: Kernel ptr Stat
-  var b: Userspace ptr Stat
-
-  # the following does not compile as the pointer types are incompatible:
-  a = b
-
-As the example shows ``ptr`` can also be used as a binary
-operator, ``region ptr T`` is a shortcut for ``ptr[region, T]``.
-
-In order to make generic code easier to write ``ptr T`` is a subtype
-of ``ptr[R, T]`` for any ``R``.
-
-Furthermore the subtype relation of the region object types is lifted to
-the pointer types: If ``A <: B`` then ``ptr[A, T] <: ptr[B, T]``. This can be
-used to model subregions of memory. As a special typing rule ``ptr[R, T]`` is
-not compatible to ``pointer`` to prevent the following from compiling:
-
-.. code-block:: nim
-  # from system
-  proc dealloc(p: pointer)
-
-  # wrap some scripting language
-  type
-    PythonsHeap = object
-    PyObjectHeader = object
-      rc: int
-      typ: pointer
-    PyObject = ptr[PythonsHeap, PyObjectHeader]
-
-  proc createPyObject(): PyObject {.importc: "...".}
-  proc destroyPyObject(x: PyObject) {.importc: "...".}
-
-  var foo = createPyObject()
-  # type error here, how convenient:
-  dealloc(foo)
-
-
-Future directions:
-
-* Memory regions might become available for  ``string`` and ``seq`` too.
-* Builtin regions like ``private``, ``global`` and ``local`` might be
-  useful for an OpenCL target.
-* Builtin "regions" can model ``lent`` and ``unique`` pointers.
-* An assignment operator can be attached to a region so that proper write
-  barriers can be generated. This would imply that the GC can be implemented
-  completely in user-space.
-
-
 Procedural type
 ---------------
 A procedural type is internally a pointer to a procedure. ``nil`` is