source: trunk/README.developer @ 2384

$Id: README.developer 2384 2010-12-22 14:03:36Z peter $

= Coding Style =

We follow the coding style described in
[http://cbbp.thep.lu.se/~jari/documents/c++_coding_guidelines/index.html C++ coding guidelines]
[http://cbbp.thep.lu.se/~jari/documents/c++_coding_guidelines/c++_coding_guidelines.pdf pdf] 
[http://cbbp.thep.lu.se/~jari/documents/c++_coding_guidelines/c++_coding_guidelines.ps postscript]
with the additions described here.

=== Subversion usage ===

Commits should be minimalistic and the project should always compile
(`make` and `make check`) when someone makes a clean checkout. There
is a short introduction to subversion and its usage available as
[http://cbbp.thep.lu.se/~jari/documents/subversion_guidelines/index.html
Subversion guidelines]. We follow these guidelines.

=== Testing ===

The test suite is run with `make check` at the project root directory
level.

The test suite should at minimum include creation of all classes (to
catch linking errors) and calls to template functions (as template
functions are not compiled until they are needed). There is a test
that checks that minimum amount of documentation is written.

For more details on writing and running tests, see file
[source:trunk/test/README test/README].

=== Interfacing [http://www.gnu.org/software/gsl/ Gnu Scientific Library, GSL] ===

The GSL documentation describes how
[http://www.gnu.org/software/gsl/manual/html_node/Error-Handling.html#Error-Handling GSL error handling]
works. The GSL library follows the thread-safe
error reporting conventions of the posix Threads library. That is,
functions return a non-zero error code to indicate an error. In most
cases yat just returns whatever the underlying GSL library calls
returns. If GSL errors occur in constructors yat handles them
accordingly. If GSL reports errors that cannot be resolved by yat a
[http://cbbp.thep.lu.se/~jari/documents/yat/classtheplu_1_1yat_1_1utility_1_1GSL__error.html GSL_error]
exception will be thrown. However, the default behaviour of
GSL library is to call abort() when unrecoverable errors occur and
puts the yat (and any other) GSL error treatment out of play. For
production environments, yat and GSL users should turn off the default
GSL error treatment by calling gsl_set_error_handler_off(), but also
when yat's GSL error treatment is preferred.

When new GSL functionality is introduced to yat, it is the
responsibility of the programmer to make sure that GSL errors are
treated properly. Proper GSL error treatment is very important in
cases when yat users turn off the default GSL error handler since:

yat aims at treating GSL errors appropriately in an
[http://www.gotw.ca/gotw/008.htm exception safe and neutral]
way but there is still some work to do before we do exceptions in a neutral way.

=== Doxygen ===
We generate our documentation using [http://www.doxygen.org Doxygen]
(version 1.5 or later). Doxygen allows several different styles. We
try to use the following style as we have found this minimizes parsing
problems:

{{{
/**
   \brief My class

   Some text documenting the class MyClass
*/
class MyClass
}}}

or similarly 

{{{
/**
   \brief magic function

   Some text documenting my_function
*/
void my_function(void);
}}}

We use doxygen keywords preceded by `\` such as `\brief`,
`\return`. All classes and functions have a brief description, which
increases clarity on summary pages.

Try to keep comment line lengths within the terminal character limit,
in other words, less than 80 characters per line. This makes the
comments more readable.

'''Internal Interface'''

Helper functions and classes that are not part of yat API should either be
labeled with doxygen flag `\internal` or placed in sub-namespace `detail`. 

= Build =

== Requirements ==

To build from a subversion checkout, you will need Autotools. More
specifically 
 * Automake 1.11 (or later)
 * Autoconf 2.63 (or later)
 * Libtool.

== Disable shared library ==

yat uses gnu Libtool in order to build shared libraries on a variety
of systems.  While this is very nice for making usable binaries, it
can be a pain when trying to debug a program. For that reason,
compilation of shared libraries can be turned off by specifying the
`--disable-shared` option to configure.

== Debugging using GDB ==

If shared library is enabled (default), libtool creates wrapper
scripts in directory test/ that call the test programs located in
directory test/.libs/. While this allows us to dynamically link against
the temporary library in yat/, it makes straightforward usage of GDB
impossible. For that reason libtool provides a wrapper:

`#> libtool --mode=execute gdb foo_test`

that sets the necessary environment variables. For more detailed
discussion, please refer to the libtool manual:

http://www.gnu.org/software/libtool/manual/libtool.html#Debugging-executables

= Versioning =

We use a softened version of [http://apr.apache.org/versioning.html APR guidelines] which
in short implies

''"The basic intent is that '''`MAJOR`''' versions are incompatible,
large-scale upgrades of the API. '''`MINOR`''' versions retain compatibility with older minor versions, and changes in the
'''`PATCH`''' level are perfectly compatible, forwards and backwards."''

== '''`MAJOR`''' Releases == 

No compatibility is guaranteed between '''`MAJOR`''' versions.

== '''`MINOR`''' Releases ==

'''`MINOR`''' versions should be compatible with earlier minor
versions. However, in the `0.x` line we may allow exceptions to this
rule, if developers agree the gain of change is sufficient. Binary compatibility is typically not guaranteed between '''`MINOR`''' versions. The `YAT_LT_VERSION` in [source:trunk/build_support/version.m4 version.m4] should reflect which versions are binary compatible. 
 
== '''`PATCH`''' Releases ==

Versions with same '''`MAJOR.MINOR`''' are perfectly compatible,
forwards and backwards.
 
This implies that only implementations can be modified in a `PATCH`
release. You cannot change the API, not even add functions or
classes because it will break forward compatibility for the previous
`PATCH` version. A `PATCH` release is a pure bug fix release

=== Backward Source Compatibility ===

Backward Source Compatibility means that an application that could build
against version `x.y` shall also build without error against
`x.y+1`. An application that compiled against header files from
previous `MINOR` version shall also compile without errors against the
header files of the new version.

Specifically this implies:
  - Do not remove any public, protected, or free functions.
  - If you modify a function, its signature must be compatible with
    previous signature, e.g., new parameters with default values may
    be added to signature.
  - Do not remove any class or inheritance for a class.

=== Backward Binary Compatibility ===

Backward Binary Compatibility means that an application that has been
compiled against version `x.y` can be linked against version
`x.y+1`. 

Specifically this implies:

  - Do not remove or modify any function (except private), not even
    add a parameter with default value because it will make the
    function incompatible with earlier header files.

  - Do not add, remove, or modify member variables, because that will
    change the allocated size of the class. Therefore, to allow
    modifications of the internal representation, it is preferable to
    hold member variable is a ''pimpl'' that is allocated privately.
    http://developer.gnome.org/doc/guides/programming-guidelines/binary.html

  - Do not add or change order among virtual functions because it will
    change the layout of the virtual table.




----------------------------------------------------------------------
{{{
Copyright (C) 2003 Jari Häkkinen, Peter Johansson
Copyright (C) 2004 Jari Häkkinen
Copyright (C) 2006, 2007, 2008, 2009 Jari Häkkinen, Peter Johansson
Copyright (C) 2010 Peter Johansson

This file is part of yat library, http://dev.thep.lu.se/yat

The yat library is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 3 of the
License, or (at your option) any later version.

The yat library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with yat. If not, see <http://www.gnu.org/licenses/>.
}}}