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doc: Move "Packaging Guidelines" under "Contributing".

* doc/guix.texi (Packaging Guidelines): Move to...
* doc/contributing.texi (Packaging Guidelines): ... here.  Turn into a
section.  Adjust references to "Contributing".
snapper
Ludovic Courtès 3 years ago
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  1. 450
      doc/contributing.texi
  2. 462
      doc/guix.texi

450
doc/contributing.texi

@ -23,6 +23,7 @@ choice.
* Building from Git:: The latest and greatest.
* Running Guix Before It Is Installed:: Hacker tricks.
* The Perfect Setup:: The right tools.
* Packaging Guidelines:: Growing the distribution.
* Coding Style:: Hygiene of the contributor.
* Submitting Patches:: Share your work.
@end menu
@ -223,6 +224,455 @@ trigger string @code{origin...}, which can be expanded further. The
@code{...}, which also can be expanded further.
@node Packaging Guidelines
@section Packaging Guidelines
@cindex packages, creating
The GNU distribution is nascent and may well lack some of your favorite
packages. This section describes how you can help make the distribution
grow.
Free software packages are usually distributed in the form of
@dfn{source code tarballs}---typically @file{tar.gz} files that contain
all the source files. Adding a package to the distribution means
essentially two things: adding a @dfn{recipe} that describes how to
build the package, including a list of other packages required to build
it, and adding @dfn{package metadata} along with that recipe, such as a
description and licensing information.
In Guix all this information is embodied in @dfn{package definitions}.
Package definitions provide a high-level view of the package. They are
written using the syntax of the Scheme programming language; in fact,
for each package we define a variable bound to the package definition,
and export that variable from a module (@pxref{Package Modules}).
However, in-depth Scheme knowledge is @emph{not} a prerequisite for
creating packages. For more information on package definitions,
@pxref{Defining Packages}.
Once a package definition is in place, stored in a file in the Guix
source tree, it can be tested using the @command{guix build} command
(@pxref{Invoking guix build}). For example, assuming the new package is
called @code{gnew}, you may run this command from the Guix build tree
(@pxref{Running Guix Before It Is Installed}):
@example
./pre-inst-env guix build gnew --keep-failed
@end example
Using @code{--keep-failed} makes it easier to debug build failures since
it provides access to the failed build tree. Another useful
command-line option when debugging is @code{--log-file}, to access the
build log.
If the package is unknown to the @command{guix} command, it may be that
the source file contains a syntax error, or lacks a @code{define-public}
clause to export the package variable. To figure it out, you may load
the module from Guile to get more information about the actual error:
@example
./pre-inst-env guile -c '(use-modules (gnu packages gnew))'
@end example
Once your package builds correctly, please send us a patch
(@pxref{Submitting Patches}). Well, if you need help, we will be happy to
help you too. Once the patch is committed in the Guix repository, the
new package automatically gets built on the supported platforms by
@url{http://hydra.gnu.org/jobset/gnu/master, our continuous integration
system}.
@cindex substituter
Users can obtain the new package definition simply by running
@command{guix pull} (@pxref{Invoking guix pull}). When
@code{@value{SUBSTITUTE-SERVER}} is done building the package, installing the
package automatically downloads binaries from there
(@pxref{Substitutes}). The only place where human intervention is
needed is to review and apply the patch.
@menu
* Software Freedom:: What may go into the distribution.
* Package Naming:: What's in a name?
* Version Numbers:: When the name is not enough.
* Synopses and Descriptions:: Helping users find the right package.
* Python Modules:: A touch of British comedy.
* Perl Modules:: Little pearls.
* Java Packages:: Coffee break.
* Fonts:: Fond of fonts.
@end menu
@node Software Freedom
@subsection Software Freedom
@c Adapted from http://www.gnu.org/philosophy/philosophy.html.
@cindex free software
The GNU operating system has been developed so that users can have
freedom in their computing. GNU is @dfn{free software}, meaning that
users have the @url{http://www.gnu.org/philosophy/free-sw.html,four
essential freedoms}: to run the program, to study and change the program
in source code form, to redistribute exact copies, and to distribute
modified versions. Packages found in the GNU distribution provide only
software that conveys these four freedoms.
In addition, the GNU distribution follow the
@url{http://www.gnu.org/distros/free-system-distribution-guidelines.html,free
software distribution guidelines}. Among other things, these guidelines
reject non-free firmware, recommendations of non-free software, and
discuss ways to deal with trademarks and patents.
Some otherwise free upstream package sources contain a small and optional
subset that violates the above guidelines, for instance because this subset
is itself non-free code. When that happens, the offending items are removed
with appropriate patches or code snippets in the @code{origin} form of the
package (@pxref{Defining Packages}). This way, @code{guix
build --source} returns the ``freed'' source rather than the unmodified
upstream source.
@node Package Naming
@subsection Package Naming
@cindex package name
A package has actually two names associated with 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 package management commands such as
@command{guix package} and @command{guix build}.
Both are usually the same and correspond to the lowercase conversion of
the project name chosen upstream, with underscores replaced with
hyphens. For instance, GNUnet is available as @code{gnunet}, and
SDL_net as @code{sdl-net}.
We do not add @code{lib} prefixes for library packages, unless these are
already part of the official project name. But @pxref{Python
Modules} and @ref{Perl Modules} for special rules concerning modules for
the Python and Perl languages.
Font package names are handled differently, @pxref{Fonts}.
@node Version Numbers
@subsection Version Numbers
@cindex package version
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:
@example
(define-public gtk+
(package
(name "gtk+")
(version "3.9.12")
...))
(define-public gtk+-2
(package
(name "gtk+")
(version "2.24.20")
...))
@end example
If we also wanted GTK+ 3.8.2, this would be packaged as
@example
(define-public gtk+-3.8
(package
(name "gtk+")
(version "3.8.2")
...))
@end example
@c See <https://lists.gnu.org/archive/html/guix-devel/2016-01/msg00425.html>,
@c for a discussion of what follows.
@cindex version number, for VCS snapshots
Occasionally, we package snapshots of upstream's version control system
(VCS) instead of formal releases. This should remain exceptional,
because it is up to upstream developers to clarify what the stable
release is. Yet, it is sometimes necessary. So, what should we put in
the @code{version} field?
Clearly, we need to make the commit identifier of the VCS snapshot
visible in the version string, but we also need to make sure that the
version string is monotonically increasing so that @command{guix package
--upgrade} can determine which version is newer. Since commit
identifiers, notably with Git, are not monotonically increasing, we add
a revision number that we increase each time we upgrade to a newer
snapshot. The resulting version string looks like this:
@example
2.0.11-3.cabba9e
^ ^ ^
| | `-- upstream commit ID
| |
| `--- Guix package revision
|
latest upstream version
@end example
It is a good idea to strip commit identifiers in the @code{version}
field to, say, 7 digits. It avoids an aesthetic annoyance (assuming
aesthetics have a role to play here) as well as problems related to OS
limits such as the maximum shebang length (127 bytes for the Linux
kernel.) It is best to use the full commit identifiers in
@code{origin}s, though, to avoid ambiguities. A typical package
definition may look like this:
@example
(define my-package
(let ((commit "c3f29bc928d5900971f65965feaae59e1272a3f7")
(revision "1")) ;Guix package revision
(package
(version (git-version "0.9" revision commit))
(source (origin
(method git-fetch)
(uri (git-reference
(url "git://example.org/my-package.git")
(commit commit)))
(sha256 (base32 "1mbikn@dots{}"))
(file-name (git-file-name name version))))
;; @dots{}
)))
@end example
@node Synopses and Descriptions
@subsection Synopses and Descriptions
@cindex package description
@cindex package synopsis
As we have seen before, each package in GNU@tie{}Guix includes a
synopsis and a description (@pxref{Defining Packages}). Synopses and
descriptions are important: They are what @command{guix package
--search} searches, and a crucial piece of information to help users
determine whether a given package suits their needs. Consequently,
packagers should pay attention to what goes into them.
Synopses must start with a capital letter and must not end with a
period. They must not start with ``a'' or ``the'', which usually does
not bring anything; for instance, prefer ``File-frobbing tool'' over ``A
tool that frobs files''. The synopsis should say what the package
is---e.g., ``Core GNU utilities (file, text, shell)''---or what it is
used for---e.g., the synopsis for GNU@tie{}grep is ``Print lines
matching a pattern''.
Keep in mind that the synopsis must be meaningful for a very wide
audience. For example, ``Manipulate alignments in the SAM format''
might make sense for a seasoned bioinformatics researcher, but might be
fairly unhelpful or even misleading to a non-specialized audience. It
is a good idea to come up with a synopsis that gives an idea of the
application domain of the package. In this example, this might give
something like ``Manipulate nucleotide sequence alignments'', which
hopefully gives the user a better idea of whether this is what they are
looking for.
Descriptions should take between five and ten lines. Use full
sentences, and avoid using acronyms without first introducing them.
Please avoid marketing phrases such as ``world-leading'',
``industrial-strength'', and ``next-generation'', and avoid superlatives
like ``the most advanced''---they are not helpful to users looking for a
package and may even sound suspicious. Instead, try to be factual,
mentioning use cases and features.
@cindex Texinfo markup, in package descriptions
Descriptions can include Texinfo markup, which is useful to introduce
ornaments such as @code{@@code} or @code{@@dfn}, bullet lists, or
hyperlinks (@pxref{Overview,,, texinfo, GNU Texinfo}). However you
should be careful when using some characters for example @samp{@@} and
curly braces which are the basic special characters in Texinfo
(@pxref{Special Characters,,, texinfo, GNU Texinfo}). User interfaces
such as @command{guix package --show} take care of rendering it
appropriately.
Synopses and descriptions are translated by volunteers
@uref{http://translationproject.org/domain/guix-packages.html, at the
Translation Project} so that as many users as possible can read them in
their native language. User interfaces search them and display them in
the language specified by the current locale.
To allow @command{xgettext} to extract them as translatable strings,
synopses and descriptions @emph{must be literal strings}. This means
that you cannot use @code{string-append} or @code{format} to construct
these strings:
@lisp
(package
;; @dots{}
(synopsis "This is translatable")
(description (string-append "This is " "*not*" " translatable.")))
@end lisp
Translation is a lot of work so, as a packager, please pay even more
attention to your synopses and descriptions as every change may entail
additional work for translators. In order to help them, it is possible
to make recommendations or instructions visible to them by inserting
special comments like this (@pxref{xgettext Invocation,,, gettext, GNU
Gettext}):
@example
;; TRANSLATORS: "X11 resize-and-rotate" should not be translated.
(description "ARandR is designed to provide a simple visual front end
for the X11 resize-and-rotate (RandR) extension. @dots{}")
@end example
@node Python Modules
@subsection Python Modules
@cindex python
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}. If the project name
starts with @code{py} (e.g.@: @code{pytz}), we keep it and prefix it as
described above.
@subsubsection Specifying Dependencies
@cindex inputs, for Python packages
Dependency information for Python packages is usually available in the
package source tree, with varying degrees of accuracy: in the
@file{setup.py} file, in @file{requirements.txt}, or in @file{tox.ini}.
Your mission, when writing a recipe for a Python package, is to map
these dependencies to the appropriate type of ``input'' (@pxref{package
Reference, inputs}). Although the @code{pypi} importer normally does a
good job (@pxref{Invoking guix import}), you may want to check the
following check list to determine which dependency goes where.
@itemize
@item
We currently package Python 2 with @code{setuptools} and @code{pip}
installed like Python 3.4 has per default. Thus you don't need to
specify either of these as an input. @command{guix lint} will warn you
if you do.
@item
Python dependencies required at run time go into
@code{propagated-inputs}. They are typically defined with the
@code{install_requires} keyword in @file{setup.py}, or in the
@file{requirements.txt} file.
@item
Python packages required only at build time---e.g., those listed with
the @code{setup_requires} keyword in @file{setup.py}---or only for
testing---e.g., those in @code{tests_require}---go into
@code{native-inputs}. The rationale is that (1) they do not need to be
propagated because they are not needed at run time, and (2) in a
cross-compilation context, it's the ``native'' input that we'd want.
Examples are the @code{pytest}, @code{mock}, and @code{nose} test
frameworks. Of course if any of these packages is also required at
run-time, it needs to go to @code{propagated-inputs}.
@item
Anything that does not fall in the previous categories goes to
@code{inputs}, for example programs or C libraries required for building
Python packages containing C extensions.
@item
If a Python package has optional dependencies (@code{extras_require}),
it is up to you to decide whether to add them or not, based on their
usefulness/overhead ratio (@pxref{Submitting Patches, @command{guix
size}}).
@end itemize
@node Perl Modules
@subsection Perl Modules
@cindex perl
Perl programs standing for themselves are named as any other package,
using the lowercase upstream name.
For Perl packages containing a single class, we use the lowercase class name,
replace all occurrences of @code{::} by dashes and prepend the prefix
@code{perl-}.
So the class @code{XML::Parser} becomes @code{perl-xml-parser}.
Modules containing several classes keep their lowercase upstream name and
are also prepended by @code{perl-}. Such modules tend to have the word
@code{perl} somewhere in their name, which gets dropped in favor of the
prefix. For instance, @code{libwww-perl} becomes @code{perl-libwww}.
@node Java Packages
@subsection Java Packages
@cindex java
Java programs standing for themselves are named as any other package,
using the lowercase upstream name.
To avoid confusion and naming clashes with other programming languages,
it is desirable that the name of a package for a Java package is
prefixed with @code{java-}. If a project already contains the word
@code{java}, we drop this; for instance, the package @code{ngsjava} is
packaged under the name @code{java-ngs}.
For Java packages containing a single class or a small class hierarchy,
we use the lowercase class name, replace all occurrences of @code{.} by
dashes and prepend the prefix @code{java-}. So the class
@code{apache.commons.cli} becomes package
@code{java-apache-commons-cli}.
@node Fonts
@subsection Fonts
@cindex fonts
For fonts that are in general not installed by a user for typesetting
purposes, or that are distributed as part of a larger software package,
we rely on the general packaging rules for software; for instance, this
applies to the fonts delivered as part of the X.Org system or fonts that
are part of TeX Live.
To make it easier for a user to search for fonts, names for other packages
containing only fonts are constructed as follows, independently of the
upstream package name.
The name of a package containing only one font family starts with
@code{font-}; it is followed by the foundry name and a dash @code{-}
if the foundry is known, and the font family name, in which spaces are
replaced by dashes (and as usual, all upper case letters are transformed
to lower case).
For example, the Gentium font family by SIL is packaged under the name
@code{font-sil-gentium}.
For a package containing several font families, the name of the collection
is used in the place of the font family name.
For instance, the Liberation fonts consist of three families,
Liberation Sans, Liberation Serif and Liberation Mono.
These could be packaged separately under the names
@code{font-liberation-sans} and so on; but as they are distributed together
under a common name, we prefer to package them together as
@code{font-liberation}.
In the case where several formats of the same font family or font collection
are packaged separately, a short form of the format, prepended by a dash,
is added to the package name. We use @code{-ttf} for TrueType fonts,
@code{-otf} for OpenType fonts and @code{-type1} for PostScript Type 1
fonts.
@node Coding Style
@section Coding Style

462
doc/guix.texi

@ -126,7 +126,6 @@ Project}.
* Installing Debugging Files:: Feeding the debugger.
* Security Updates:: Deploying security fixes quickly.
* Package Modules:: Packages from the programmer's viewpoint.
* Packaging Guidelines:: Growing the distribution.
* Bootstrapping:: GNU/Linux built from scratch.
* Porting:: Targeting another platform or kernel.
* Contributing:: Your help needed!
@ -282,17 +281,6 @@ Defining Services
* Service Reference:: API reference.
* Shepherd Services:: A particular type of service.
Packaging Guidelines
* Software Freedom:: What may go into the distribution.
* Package Naming:: What's in a name?
* Version Numbers:: When the name is not enough.
* Synopses and Descriptions:: Helping users find the right package.
* Python Modules:: A touch of British comedy.
* Perl Modules:: Little pearls.
* Java Packages:: Coffee break.
* Fonts:: Fond of fonts.
@end detailmenu
@end menu
@ -24180,456 +24168,6 @@ distribution. The root of this dependency graph is a small set of
bootstrap)} module. For more information on bootstrapping,
@pxref{Bootstrapping}.
@node Packaging Guidelines
@chapter Packaging Guidelines
@cindex packages, creating
The GNU distribution is nascent and may well lack some of your favorite
packages. This section describes how you can help make the distribution
grow. @xref{Contributing}, for additional information on how you can
help.
Free software packages are usually distributed in the form of
@dfn{source code tarballs}---typically @file{tar.gz} files that contain
all the source files. Adding a package to the distribution means
essentially two things: adding a @dfn{recipe} that describes how to
build the package, including a list of other packages required to build
it, and adding @dfn{package metadata} along with that recipe, such as a
description and licensing information.
In Guix all this information is embodied in @dfn{package definitions}.
Package definitions provide a high-level view of the package. They are
written using the syntax of the Scheme programming language; in fact,
for each package we define a variable bound to the package definition,
and export that variable from a module (@pxref{Package Modules}).
However, in-depth Scheme knowledge is @emph{not} a prerequisite for
creating packages. For more information on package definitions,
@pxref{Defining Packages}.
Once a package definition is in place, stored in a file in the Guix
source tree, it can be tested using the @command{guix build} command
(@pxref{Invoking guix build}). For example, assuming the new package is
called @code{gnew}, you may run this command from the Guix build tree
(@pxref{Running Guix Before It Is Installed}):
@example
./pre-inst-env guix build gnew --keep-failed
@end example
Using @code{--keep-failed} makes it easier to debug build failures since
it provides access to the failed build tree. Another useful
command-line option when debugging is @code{--log-file}, to access the
build log.
If the package is unknown to the @command{guix} command, it may be that
the source file contains a syntax error, or lacks a @code{define-public}
clause to export the package variable. To figure it out, you may load
the module from Guile to get more information about the actual error:
@example
./pre-inst-env guile -c '(use-modules (gnu packages gnew))'
@end example
Once your package builds correctly, please send us a patch
(@pxref{Contributing}). Well, if you need help, we will be happy to
help you too. Once the patch is committed in the Guix repository, the
new package automatically gets built on the supported platforms by
@url{http://hydra.gnu.org/jobset/gnu/master, our continuous integration
system}.
@cindex substituter
Users can obtain the new package definition simply by running
@command{guix pull} (@pxref{Invoking guix pull}). When
@code{@value{SUBSTITUTE-SERVER}} is done building the package, installing the
package automatically downloads binaries from there
(@pxref{Substitutes}). The only place where human intervention is
needed is to review and apply the patch.
@menu
* Software Freedom:: What may go into the distribution.
* Package Naming:: What's in a name?
* Version Numbers:: When the name is not enough.
* Synopses and Descriptions:: Helping users find the right package.
* Python Modules:: A touch of British comedy.
* Perl Modules:: Little pearls.
* Java Packages:: Coffee break.
* Fonts:: Fond of fonts.
@end menu
@node Software Freedom
@section Software Freedom
@c Adapted from http://www.gnu.org/philosophy/philosophy.html.
@cindex free software
The GNU operating system has been developed so that users can have
freedom in their computing. GNU is @dfn{free software}, meaning that
users have the @url{http://www.gnu.org/philosophy/free-sw.html,four
essential freedoms}: to run the program, to study and change the program
in source code form, to redistribute exact copies, and to distribute
modified versions. Packages found in the GNU distribution provide only
software that conveys these four freedoms.
In addition, the GNU distribution follow the
@url{http://www.gnu.org/distros/free-system-distribution-guidelines.html,free
software distribution guidelines}. Among other things, these guidelines
reject non-free firmware, recommendations of non-free software, and
discuss ways to deal with trademarks and patents.
Some otherwise free upstream package sources contain a small and optional
subset that violates the above guidelines, for instance because this subset
is itself non-free code. When that happens, the offending items are removed
with appropriate patches or code snippets in the @code{origin} form of the
package (@pxref{Defining Packages}). This way, @code{guix
build --source} returns the ``freed'' source rather than the unmodified
upstream source.
@node Package Naming
@section Package Naming
@cindex package name
A package has actually two names associated with 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 package management commands such as
@command{guix package} and @command{guix build}.
Both are usually the same and correspond to the lowercase conversion of
the project name chosen upstream, with underscores replaced with
hyphens. For instance, GNUnet is available as @code{gnunet}, and
SDL_net as @code{sdl-net}.
We do not add @code{lib} prefixes for library packages, unless these are
already part of the official project name. But @pxref{Python
Modules} and @ref{Perl Modules} for special rules concerning modules for
the Python and Perl languages.
Font package names are handled differently, @pxref{Fonts}.
@node Version Numbers
@section Version Numbers
@cindex package version
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:
@example
(define-public gtk+
(package
(name "gtk+")
(version "3.9.12")
...))
(define-public gtk+-2
(package
(name "gtk+")
(version "2.24.20")
...))
@end example
If we also wanted GTK+ 3.8.2, this would be packaged as
@example
(define-public gtk+-3.8
(package
(name "gtk+")
(version "3.8.2")
...))
@end example
@c See <https://lists.gnu.org/archive/html/guix-devel/2016-01/msg00425.html>,
@c for a discussion of what follows.
@cindex version number, for VCS snapshots
Occasionally, we package snapshots of upstream's version control system
(VCS) instead of formal releases. This should remain exceptional,
because it is up to upstream developers to clarify what the stable
release is. Yet, it is sometimes necessary. So, what should we put in
the @code{version} field?
Clearly, we need to make the commit identifier of the VCS snapshot
visible in the version string, but we also need to make sure that the
version string is monotonically increasing so that @command{guix package
--upgrade} can determine which version is newer. Since commit
identifiers, notably with Git, are not monotonically increasing, we add
a revision number that we increase each time we upgrade to a newer
snapshot. The resulting version string looks like this:
@example
2.0.11-3.cabba9e
^ ^ ^
| | `-- upstream commit ID
| |
| `--- Guix package revision
|
latest upstream version
@end example
It is a good idea to strip commit identifiers in the @code{version}
field to, say, 7 digits. It avoids an aesthetic annoyance (assuming
aesthetics have a role to play here) as well as problems related to OS
limits such as the maximum shebang length (127 bytes for the Linux
kernel.) It is best to use the full commit identifiers in
@code{origin}s, though, to avoid ambiguities. A typical package
definition may look like this:
@example
(define my-package
(let ((commit "c3f29bc928d5900971f65965feaae59e1272a3f7")
(revision "1")) ;Guix package revision
(package
(version (git-version "0.9" revision commit))
(source (origin
(method git-fetch)
(uri (git-reference
(url "git://example.org/my-package.git")
(commit commit)))
(sha256 (base32 "1mbikn@dots{}"))
(file-name (git-file-name name version))))
;; @dots{}
)))
@end example
@node Synopses and Descriptions
@section Synopses and Descriptions
@cindex package description
@cindex package synopsis
As we have seen before, each package in GNU@tie{}Guix includes a
synopsis and a description (@pxref{Defining Packages}). Synopses and
descriptions are important: They are what @command{guix package
--search} searches, and a crucial piece of information to help users
determine whether a given package suits their needs. Consequently,
packagers should pay attention to what goes into them.
Synopses must start with a capital letter and must not end with a
period. They must not start with ``a'' or ``the'', which usually does
not bring anything; for instance, prefer ``File-frobbing tool'' over ``A
tool that frobs files''. The synopsis should say what the package
is---e.g., ``Core GNU utilities (file, text, shell)''---or what it is
used for---e.g., the synopsis for GNU@tie{}grep is ``Print lines
matching a pattern''.
Keep in mind that the synopsis must be meaningful for a very wide
audience. For example, ``Manipulate alignments in the SAM format''
might make sense for a seasoned bioinformatics researcher, but might be
fairly unhelpful or even misleading to a non-specialized audience. It
is a good idea to come up with a synopsis that gives an idea of the
application domain of the package. In this example, this might give
something like ``Manipulate nucleotide sequence alignments'', which
hopefully gives the user a better idea of whether this is what they are
looking for.
Descriptions should take between five and ten lines. Use full
sentences, and avoid using acronyms without first introducing them.
Please avoid marketing phrases such as ``world-leading'',
``industrial-strength'', and ``next-generation'', and avoid superlatives
like ``the most advanced''---they are not helpful to users looking for a
package and may even sound suspicious. Instead, try to be factual,
mentioning use cases and features.
@cindex Texinfo markup, in package descriptions
Descriptions can include Texinfo markup, which is useful to introduce
ornaments such as @code{@@code} or @code{@@dfn}, bullet lists, or
hyperlinks (@pxref{Overview,,, texinfo, GNU Texinfo}). However you
should be careful when using some characters for example @samp{@@} and
curly braces which are the basic special characters in Texinfo
(@pxref{Special Characters,,, texinfo, GNU Texinfo}). User interfaces
such as @command{guix package --show} take care of rendering it
appropriately.
Synopses and descriptions are translated by volunteers
@uref{http://translationproject.org/domain/guix-packages.html, at the
Translation Project} so that as many users as possible can read them in
their native language. User interfaces search them and display them in
the language specified by the current locale.
To allow @command{xgettext} to extract them as translatable strings,
synopses and descriptions @emph{must be literal strings}. This means
that you cannot use @code{string-append} or @code{format} to construct
these strings:
@lisp
(package
;; @dots{}
(synopsis "This is translatable")
(description (string-append "This is " "*not*" " translatable.")))
@end lisp
Translation is a lot of work so, as a packager, please pay even more
attention to your synopses and descriptions as every change may entail
additional work for translators. In order to help them, it is possible
to make recommendations or instructions visible to them by inserting
special comments like this (@pxref{xgettext Invocation,,, gettext, GNU
Gettext}):
@example
;; TRANSLATORS: "X11 resize-and-rotate" should not be translated.
(description "ARandR is designed to provide a simple visual front end
for the X11 resize-and-rotate (RandR) extension. @dots{}")
@end example
@node Python Modules
@section Python Modules
@cindex python
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}. If the project name
starts with @code{py} (e.g.@: @code{pytz}), we keep it and prefix it as
described above.
@subsection Specifying Dependencies
@cindex inputs, for Python packages
Dependency information for Python packages is usually available in the
package source tree, with varying degrees of accuracy: in the
@file{setup.py} file, in @file{requirements.txt}, or in @file{tox.ini}.
Your mission, when writing a recipe for a Python package, is to map
these dependencies to the appropriate type of ``input'' (@pxref{package
Reference, inputs}). Although the @code{pypi} importer normally does a
good job (@pxref{Invoking guix import}), you may want to check the
following check list to determine which dependency goes where.
@itemize
@item
We currently package Python 2 with @code{setuptools} and @code{pip}
installed like Python 3.4 has per default. Thus you don't need to
specify either of these as an input. @command{guix lint} will warn you
if you do.
@item
Python dependencies required at run time go into
@code{propagated-inputs}. They are typically defined with the
@code{install_requires} keyword in @file{setup.py}, or in the
@file{requirements.txt} file.
@item
Python packages required only at build time---e.g., those listed with
the @code{setup_requires} keyword in @file{setup.py}---or only for
testing---e.g., those in @code{tests_require}---go into
@code{native-inputs}. The rationale is that (1) they do not need to be
propagated because they are not needed at run time, and (2) in a
cross-compilation context, it's the ``native'' input that we'd want.
Examples are the @code{pytest}, @code{mock}, and @code{nose} test
frameworks. Of course if any of these packages is also required at
run-time, it needs to go to @code{propagated-inputs}.
@item
Anything that does not fall in the previous categories goes to
@code{inputs}, for example programs or C libraries required for building
Python packages containing C extensions.
@item
If a Python package has optional dependencies (@code{extras_require}),
it is up to you to decide whether to add them or not, based on their
usefulness/overhead ratio (@pxref{Submitting Patches, @command{guix
size}}).
@end itemize
@node Perl Modules
@section Perl Modules
@cindex perl
Perl programs standing for themselves are named as any other package,
using the lowercase upstream name.
For Perl packages containing a single class, we use the lowercase class name,
replace all occurrences of @code{::} by dashes and prepend the prefix
@code{perl-}.
So the class @code{XML::Parser} becomes @code{perl-xml-parser}.
Modules containing several classes keep their lowercase upstream name and
are also prepended by @code{perl-}. Such modules tend to have the word
@code{perl} somewhere in their name, which gets dropped in favor of the
prefix. For instance, @code{libwww-perl} becomes @code{perl-libwww}.
@node Java Packages
@section Java Packages
@cindex java
Java programs standing for themselves are named as any other package,
using the lowercase upstream name.
To avoid confusion and naming clashes with other programming languages,
it is desirable that the name of a package for a Java package is
prefixed with @code{java-}. If a project already contains the word
@code{java}, we drop this; for instance, the package @code{ngsjava} is
packaged under the name @code{java-ngs}.
For Java packages containing a single class or a small class hierarchy,
we use the lowercase class name, replace all occurrences of @code{.} by
dashes and prepend the prefix @code{java-}. So the class
@code{apache.commons.cli} becomes package
@code{java-apache-commons-cli}.
@node Fonts
@section Fonts
@cindex fonts
For fonts that are in general not installed by a user for typesetting
purposes, or that are distributed as part of a larger software package,
we rely on the general packaging rules for software; for instance, this
applies to the fonts delivered as part of the X.Org system or fonts that
are part of TeX Live.
To make it easier for a user to search for fonts, names for other packages
containing only fonts are constructed as follows, independently of the
upstream package name.
The name of a package containing only one font family starts with
@code{font-}; it is followed by the foundry name and a dash @code{-}
if the foundry is known, and the font family name, in which spaces are
replaced by dashes (and as usual, all upper case letters are transformed
to lower case).
For example, the Gentium font family by SIL is packaged under the name
@code{font-sil-gentium}.
For a package containing several font families, the name of the collection
is used in the place of the font family name.
For instance, the Liberation fonts consist of three families,
Liberation Sans, Liberation Serif and Liberation Mono.
These could be packaged separately under the names
@code{font-liberation-sans} and so on; but as they are distributed together
under a common name, we prefer to package them together as
@code{font-liberation}.
In the case where several formats of the same font family or font collection
are packaged separately, a short form of the format, prepended by a dash,
is added to the package name. We use @code{-ttf} for TrueType fonts,
@code{-otf} for OpenType fonts and @code{-type1} for PostScript Type 1
fonts.
@node Bootstrapping
@chapter Bootstrapping

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