.. mode: -*- rst -*-

Library version mechanism
=========================

:Tag: design.mps.version-library
:Author: David Jones
:Date: 1998-08-19
:Status: incomplete document
:Revision: $Id: //info.ravenbrook.com/project/mps/version/1.113/design/version-library.txt#1 $
:Copyright: See `Copyright and License`_.
:Index terms:   pair: library version mechanism; design


Introduction
------------

_`.intro`: This describes the design of a mechanism to be used to
determine the version (that is, product, version, and release) of an
MPS library.


Readership
----------

_`.readership`: Any MPS developer.


Source
------

_`.source`: Various requirements demand such a mechanism. See
request.epcore.160021_: There is no way to tell which version and
release of the MM one is using.

.. _request.epcore.160021: https://info.ravenbrook.com/project/mps/import/2001-11-05/mmprevol/request/epcore/160021

Overview
--------

_`.overview`: See design.mps.version for discussion and design of
versions of other aspects of the software. This document concentrates
on a design for determining which version of the library one has
linked with. There are two aspects to the design, allowing humans to
determine the version of an MPS library, and allowing programs to
determine the version of an MPS library. Only the former is currently
designed (a method for humans to determine which version of an MPS
library is being used).

_`.overview.impl`: The overall design is to have a distinctive string
compiled into the library binary. Various programs and tools will be
able to extract the string and display it. The string will identify
the version of the MPS begin used.


Architecture
------------

_`.arch.structure`: The design consists of three components:

#. _`.arch.string`: A string embedded into any delivered library
   binaries (which will encode the necessary information).

#. _`.arch.proc`: A process by which the string is modified
   appropriately whenever releases are made.

#. _`.arch.tool`: A tool and its documentation (it is expected that
   standard tools can be used). The tool will be used to extract the
   version string from a delivered library or an executable linked
   with the library.

_`.arch.not-here`: Only the string component
(arch.string) is directly described here. The other
components are described elsewhere. (where?)

The string will contain information to identify the following items:

#. _`.arch.string.platform`: the platform being used.

#. _`.arch.string.product`: the name of the product.

#. _`.arch.string.variety`: the variety of the product.

#. _`.arch.string.version`: the version and release of the product.


Implementation
--------------

_`.impl.file`: The string itself is a declared C object in the file
``version.c`` (impl.c.version). It consists of a concatenation of
various strings which are defined in other modules.

_`.impl.variety`: The string containing the name of the variety is the
expansion of the macro ``MPS_VARIETY_STRING`` defined by ``config.h``
(impl.h.config).

_`.impl.product`: The string containing the name of the product is the
expansion of the macro ``MPS_PROD_STRING`` defined by ``config.h``
(impl.h.config).

_`.impl.platform`: The string containing the name of the platform is
the expansion of the macro ``MPS_PF_STRING`` defined by ``mpstd.h``
(impl.h.mpstd).

_`.impl.date`: The string contains the date and time of compilation by
using the ``__DATE__`` and ``__TIME__`` macros defined by ISO C
§6.8.8.

_`.impl.version`: The string contains the version and release of the
product. This is by the expansion of the macro ``MPS_RELEASE`` which
is defined in this module (``version.c``).

_`.impl.usage`: To make a release, the ``MPS_RELEASE`` macro (see
impl.c.version.release) is edited to contain the release name (for
example, ``"release.epcore.brisling"``), and then changed back
immediately after the release checkpoint is made.


Document History
----------------

- 1998-08-19 David Jones. Incomplete document.

- 2002-06-07 RB_ Converted from MMInfo database design document.

- 2013-03-11 GDR_ Converted to reStructuredText.

.. _RB: http://www.ravenbrook.com/consultants/rb/
.. _GDR: http://www.ravenbrook.com/consultants/gdr/


Copyright and License
---------------------

Copyright © 2013-2014 Ravenbrook Limited. All rights reserved.
<http://www.ravenbrook.com/>. This is an open source license. Contact
Ravenbrook for commercial licensing options.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

#. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.

#. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.

#. Redistributions in any form must be accompanied by information on how
   to obtain complete source code for this software and any
   accompanying software that uses this software.  The source code must
   either be included in the distribution or be available for no more than
   the cost of distribution plus a nominal fee, and must be freely
   redistributable under reasonable conditions.  For an executable file,
   complete source code means the source code for all modules it contains.
   It does not include source code for modules or files that typically
   accompany the major components of the operating system on which the
   executable file runs.

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