If you are producing code to add new functionality to Sage, you might consider turning it into a package (an “spkg”) instead of a patch file. If your code is very large (for instance) and should be offered as an optional download, a package is the right choice. Similarly, if your code depends on some other optional component of Sage, you should produce a package. When in doubt, ask for advice on the sage-devel mailing list.
This chapter covers issues relevant to producing a package. The directory structure of a package is discussed along with scripts for installing a package and running the test suite (if any) contained in an upstream project’s source distribution. For guidelines on patching an existing Sage package, see the chapter Patching a Sage Package.
The abbreviation “spkg” stands for “Sage package”. The directory SAGE_ROOT/spkg/standard contains spkg’s. In a source install, these are all Sage spkg files (actually .tar or .tar.bz2 files), which are the source code that defines Sage. In a binary install, some of these may be small placeholder files to save space.
Sage packages are distributed as .spkg files, which are .tar.bz2 files (or tar files) but have the extension .spkg to discourage confusion. Although Sage packages are packed using tar and/or bzip2, note that .spkg files contain control information (installation scripts and metadata) that are necessary for building and installing them. For source distributions, when you compile Sage the file SAGE_ROOT/makefile takes care of the unpacking, compilation, and installation of Sage packages for you. You can type
tar -jxvf mypackage-version.spkg
to extract an spkg and see what is inside. If you want to create a new Sage package, it is recommended that you start by examining some existing spkg’s. In a source distribution of Sage, the standard spkg’s can be found under SAGE_ROOT/spkg/standard/. The URL http://www.sagemath.org/download-packages.html lists standard spkg’s available for download.
Each Sage spkg has a name of the following form:
BASENAME-VERSION.spkg
BASENAME is the name of the package; it may contain lower-case letters, numbers, and underscores, but no hyphens. VERSION is the version number; it should start with a number and may contain numbers, letters, dots, and hyphens; it may end in a string of the form “pNUM”, where “NUM” is a non-negative integer. If your spkg is a “vanilla” (unmodified) version of some piece of software, say version 5.3 of “my-python-package”, then BASENAME would be “my_python_package” – note the change from hyphens to underscores, because BASENAME should not contain any hyphens – and VERSION would be “5.3”. If you need to modify the software to use it with Sage (as described below and in the chapter Patching a Sage Package), then VERSION would be “5.3.p0”, the “p0” indicating a patch-level of 0. If someone adds more patches, later, this would become “p1”, then “p2”, etc.
The string VERSION must be present. If you are using a piece software with no obvious version number, use a date: you can see several such names among the standard Sage packages: http://www.sagemath.org/packages/standard/.
To give your spkg a name like this, create a directory called BASENAME-VERSION and put your files in that directory – the next section describes the directory structure.
Put your files in a directory with a name like mypackage-0.1, as described above. If you are porting another software package, then the directory should contain a subdirectory src/, containing an unaltered copy of the package. Every file not in src/ should be under version control, i.e. checked into an hg repository.
More precisely, the directory should contain the following:
src/: this directory contains vanilla upstream code, with a few exceptions, e.g. when the spkg shipped with Sage is in effect upstream, and development on that code base is happening in close coordination with Sage. See John Cremona’s eclib spkg, for instance. The directory src/ must not be under revision control.
.hg, .hgignore, and .hgtags: The Sage project uses Mercurial for its revision control system (see Producing Patches with Mercurial). The hidden directory .hg is part of the standard Sage spkg layout. It contains the Mercurial repository for all files not in the src/ directory.
The files .hgignore and .hgtags also belong to the Mercurial repository. The file .hgtags is optional, and is frequently omitted. You should make sure that the file .hgignore contains “src/”, since we are not tracking its content. Indeed, frequently this file contains only a single line,
src/
spkg-install: this file contains the install script. See below for more information and a template.
SPKG.txt: this file describes the spkg in wiki format. Each new revision needs an updated changelog entry or the spkg will get an automatic “needs work” at review time. See below for a template.
spkg-check: this file runs the test suite. This is somewhat optional since not all spkg’s have test suites. If possible, do create such a script since it helps isolate bugs in upstream packages
patches/: this directory contains patched versions of upstream source files under src/. Each file requiring changes (e.g. foo.c) must have a diff against the original file (e.g. foo.c.patch) for easy rebases against new upstream source releases. Updated files should be copied into the right place under src/ at the start of spkg-install. Please document all patches in SPKG.txt, i.e. what they do, if they are platform specific, if they should be pushed upstream, etc. To ensure that all patched versions of upstream source files under src/ are under revision control, the whole directory patches/ must be under revision control.
Never apply patches to upstream source files under src/ and then package up an spkg. Such a mixture of upstream source with Sage specific patched versions is a recipe for confusion. There must be a clean separation between the source provided by the upstream project and the patched versions that the Sage project generates based on top of the upstream source.
The script spkg-install is run during installation of the Sage package. In this script, you may make the following assumptions:
The PATH has the locations of sage and python (from the Sage installation) at the front. Thus the command
python setup.py install
will run the correct version of Python with everything set up correctly. Also, running gap or Singular, for example, will run the correct version.
The environment variable SAGE_ROOT points to the root directory of the Sage installation.
The environment variable SAGE_LOCAL points to the SAGE_ROOT/local directory of the Sage installation.
The environment variables LD_LIBRARY_PATH and DYLD_LIBRARY_PATH both have SAGE_ROOT/local/lib at the front.
The spkg-install script should copy your files to the appropriate place after doing any build that is necessary. Here is a template:
#!/usr/bin/env bash
if [ "$SAGE_LOCAL" = "" ]; then
echo "SAGE_LOCAL undefined ... exiting";
echo "Maybe run 'sage -sh'?"
exit 1
fi
cd src
./configure --prefix="$SAGE_LOCAL"
if [ $? -ne 0 ]; then
echo "Error configuring PACKAGE_NAME."
exit 1
fi
make
if [ $? -ne 0 ]; then
echo "Error building PACKAGE_NAME."
exit 1
fi
make install
if [ $? -ne 0 ]; then
echo "Error installing PACKAGE_NAME."
exit 1
fi
Note that the first line is /usr/bin/env bash; this is important for portability. Next, the script checks that SAGE_LOCAL is defined to make sure that the Sage environment has been set. After this, the script may simply run cd src and then call either python setup.py install or the autotools sequence ./configure && make && make install, or something else along these lines.
Often, though, it can be more complicated. For example, it is often necessary to apply the patches from the patches directory. Also, you should first build (e.g. with python setup.py build, exiting if there is an error, before installing (e.g. with python setup.py install). In this way, you would not overwrite a working older version with a non-working newer version of the spkg.
The SPKG.txt file should follow this pattern:
= name of spkg =
== Description ==
Describe the package here.
== License ==
Describe the package's license here.
== SPKG Maintainers ==
List the maintainers here
== Upstream Contact ==
Provide information for upstream contact.
== Dependencies ==
List the dependencies here
== Special Update/Build Instructions ==
List patches that need to be applied and what they do
== Changelog ==
Provide a changelog of the spkg here.
When the directory (say, mypackage-0.1) is ready, the command
sage -pkg mypackage-0.1
will create the file mypackage-0.1.spkg. As noted above, this creates a compressed tar file. Running sage -pkg_nc mypackage-0.1 creates an uncompressed tar file.
When your spkg is ready, you should post about it on sage-devel. If people there think it is a good idea, then post a link to the spkg on the Sage trac server (see The Sage Trac Server: Submitting Patches and Packages) so it can be refereed. Do not post the spkg itself to the trac server. You only need to provide a link to your spkg. If your spkg gets a positive review, it might be included into the core Sage library, or it might become an optional download from the Sage website, so anybody can automatically install it by typing sage -i mypackage-version.spkg.
Note
There are usually a number of things to do for all spkgs:
Note
If your package depends on another package, say boehmgc, then you should check that this other package has been installed. Your spkg-install script should check that it exists, with code like the following:
BOEHM_GC=`cd $SAGE_ROOT/spkg/standard/; ./newest_version boehm_gc`
if [ $? -ne 0 ]; then
echo "Failed to find boehm_gc. Please install the boehm_gc spkg"
exit 1
fi
Caveat: Do not just copy to e.g. SAGE_ROOT/local/lib/gap*/ since that will copy your package to the lib directory of the old version of GAP if GAP is upgraded.
External Magma code goes in SAGE_ROOT/data/extcode/magma/user, so if you want to redistribute Magma code with Sage as a package that Magma-enabled users can use, that is where you would put it. You would also want to have relevant Python code to make the Magma code easily usable.
This section contains some guidelines on what an spkg must never do to a Sage installation. You are encouraged to produce an spkg that is as self-contained as possible.