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doc: Add package guidelines for names and numbers.

* doc/guix.texi: Three new subsections.
Andreas Enge 8 years ago
  1. 82


@ -1631,7 +1631,10 @@ needed is to review and apply the patch.
* Software Freedom:: What may go into the distribution.
* Software Freedom:: What may go into the distribution.
* Package Naming:: What's in a name?
* Version Numbers:: When the name is not enough.
* Python Modules:: Taming the snake.
@end menu
@node Software Freedom
@ -1654,6 +1657,83 @@ reject non-free firmware, recommendations of non-free software, and
discuss ways to deal with trademarks and patents.
@node Package Naming
@subsection Package Naming
A package has actually two names associated to it:
First, there is the name of the @emph{Scheme variable}, the one following
@code{define-public}. By this name, the package can be made known in the
Scheme code, for instance as input to another package.
Second, there is the string in the @code{name} field of a package definition.
This name is used by the package manager.
Both are usually the same and correspond to the lowercase conversion of the
project name chosen by upstream. For instance, the GNUnet project is packaged
as @code{gnunet}. We do not add @code{lib} prefixes for library packages,
unless these are already part of the official project name.
But see @ref{Python Modules} for special rules concerning modules for
the Python language.
@node Version Numbers
@subsection Version Numbers
We usually package only the latest version of a given free software
project. But sometimes, for instance for incompatible library versions,
two (or more) versions of the same package are needed. These require different
Scheme variable names. We use the name as defined in @ref {Package Naming}
for the most recent version; previous versions use the same name, suffixed
by @code{-} and the smallest prefix of the version number that may
distinguish the two versions.
The name inside the package definition is the same for all versions of a
package and does not contain any version number.
For instance, the versions 2.24.20 and 3.9.12 of GTK+ may be packaged as follows:
(define-public gtk+
(name "gtk+")
(version "3.9.12")
(define-public gtk+-2
(name "gtk+")
(version "2.24.20")
@end example
If we also wanted GTK+ 3.8.2, this would be packaged as
(define-public gtk+-3.8
(name "gtk+")
(version "3.8.2")
@end example
@node Python Modules
@subsection Python Modules
We currently package Python 2 and Python 3, under the Scheme variable names
@code{python-2} and @code{python} as explained in @ref{Version Numbers}.
To avoid confusion and naming clashes with other programming languages, it
seems desirable that the name of a package for a Python module contains
the word @code{python}.
Some modules are compatible with only one version of Python, others with both.
If the package Foo compiles only with Python 3, we name it
@code{python-foo}; if it compiles only with Python 2, we name it
@code{python2-foo}. If it is compatible with both versions, we create two
packages with the corresponding names.
If a project already contains the word @code{python}, we drop this;
for instance, the module python-dateutil is packaged under the names
@code{python-dateutil} and @code{python2-dateutil}.
@node Bootstrapping
@section Bootstrapping