Merge pull request #663 from citibeth/efischer/160327-DocumentationIm…

…provements

[RtM] Documentation Improvements

lib/spack/docs/basic_usage.rst

@@ -6,6 +6,15 @@ Basic usage
 The ``spack`` command has many *subcommands*.  You'll only need a
 small subset of them for typical usage.
 
+Note that Spack colorizes output.  ``less -R`` should be used with
+Spack to maintian this colorization.  Eg::
+
+    spack find | less -R
+
+It is recommend that the following be put in your ``.bashrc`` file::
+
+    alias less='less -R'
+
 
 Listing available packages
 ------------------------------

lib/spack/docs/case_studies.rst

@@ -0,0 +1,167 @@
+Using Spack for CMake-based Development
+==========================================
+
+These are instructions on how to use Spack to aid in the development
+of a CMake-based project.  Spack is used to help find the dependencies
+for the project, configure it at development time, and then package it
+it in a way that others can install.  Using Spack for CMake-based
+development consists of three parts:
+
+1. Setting up the CMake build in your software
+2. Writing the Spack Package
+3. Using it from Spack.
+
+
+Setting Up the CMake Build
+---------------------------------------
+
+You should follow standard CMake conventions in setting up your
+software, your CMake build should NOT depend on or require Spack to
+build.  See here for an example:
+   https://github.com/citibeth/icebin
+
+Note that there's one exception here to the rule I mentioned above.
+In ``CMakeLists.txt``, I have the following line::
+
+    include_directories($ENV{CMAKE_TRANSITIVE_INCLUDE_PATH})
+
+
+This is a hook into Spack, and it ensures that all transitive
+dependencies are included in the include path.  It's not needed if
+everything is in one tree, but it is (sometimes) in the Spack world;
+when running without Spack, it has no effect.
+
+Note that this "feature" is controversial, could break with future
+versions of GNU ld, and probably not the best to use.  The best
+practice is that you make sure that anything you #include is listed as
+a dependency in your CMakeLists.txt.
+
+To be more specific: if you #inlcude something from package A and an
+installed HEADER FILE in A #includes something from package B, then
+you should also list B as a dependency in your CMake build.  If you
+depend on A but header files exported by A do NOT #include things from
+B, then you do NOT need to list B as a dependency --- even if linking
+to A links in libB.so as well.
+
+I also recommend that you set up your CMake build to use RPATHs
+correctly.  Not only is this a good idea and nice, but it also ensures
+that your package will build the same with or without ``spack
+install``.
+
+Writing the Spack Package
+---------------------------------------
+
+Now that you have a CMake build, you want to tell Spack how to
+configure it.  This is done by writing a Spack package for your
+software.  See here for example:
+   https://github.com/citibeth/spack/blob/efischer/develop/var/spack/repos/builtin/packages/icebin/package.py
+
+You need to subclass ``CMakePackage``, as is done in this example.
+This enables advanced features of Spack for helping you in configuring
+your software (keep reading...).  Instead of an ``install()`` method
+used when subclassing ``Package``, you write ``configure_args()``.
+See here for more info on how this works:
+   https://github.com/LLNL/spack/pull/543/files
+
+NOTE: if your software is not publicly available, you do not need to
+set the URL or version.  Or you can set up bogus URLs and
+versions... whatever causes Spack to not crash.
+
+
+Using it from Spack
+--------------------------------
+
+Now that you have a Spack package, you can get Spack to setup your
+CMake project for you.  Use the following to setup, configure and
+build your project::
+
+    cd myproject
+    spack spconfig myproject@local
+    mkdir build; cd build
+    ../spconfig.py ..
+    make
+    make install
+
+
+Everything here should look pretty familiar here from a CMake
+perspective, except that ``spack spconfig`` creates the file
+``spconfig.py``, which calls CMake with arguments appropriate for your
+Spack configuration.  Think of it as the equivalent to running a bunch
+of ``spack location -i`` commands.  You will run ``spconfig.py``
+instead of running CMake directly.
+
+If your project is publicly available (eg on GitHub), then you can
+ALSO use this setup to "just install" a release version without going
+through the manual configuration/build step.  Just do:
+
+1. Put tag(s) on the version(s) in your GitHub repo you want to be release versions.
+
+2. Set the ``url`` in your ``package.py`` to download a tarball for
+   the appropriate version.  (GitHub will give you a tarball for any
+   version in the repo, if you tickle it the right way).  For example::
+
+    https://github.com/citibeth/icebin/tarball/v0.1.0
+
+   Set up versions as appropriate in your ``package.py``.  (Manually
+   download the tarball and run ``md5sum`` to determine the
+   appropriate checksum for it).
+
+3. Now you should be able to say ``spack install myproject@version``
+   and things "just work."
+
+NOTE... in order to use the features outlined in this post, you
+currently need to use the following branch of Spack:
+   https://github.com/citibeth/spack/tree/efischer/develop
+
+There is a pull request open on this branch (
+https://github.com/LLNL/spack/pull/543 ) and we are working to get it
+integrated into the main ``develop`` branch.
+
+
+Activating your Software
+-------------------------------------
+
+Once you've built your software, you will want to load it up.  You can
+use ``spack load mypackage@local`` for that in your ``.bashrc``, but
+that is slow.  Try stuff like the following instead:
+
+The following command will load the Spack-installed packages needed
+for basic Python use of IceBin::
+
+    module load `spack module find tcl icebin netcdf cmake@3.5.1`
+    module load `spack module find --dependencies tcl py-basemap py-giss`
+
+
+You can speed up shell startup by turning these into ``module load`` commands.
+
+1. Cut-n-paste the script ``make_spackenv``::
+
+    #!/bin/sh
+    #
+    # Generate commands to load the Spack environment
+
+    SPACKENV=$HOME/spackenv.sh
+
+    spack module find --shell tcl git icebin@local ibmisc netcdf cmake@3.5.1 >$SPACKENV
+    spack module find --dependencies --shell tcl py-basemap py-giss >>$SPACKENV
+
+2. Add the following to your ``.bashrc`` file::
+
+    source $HOME/spackenv.sh
+    # Preferentially use your checked-out Python source
+    export PYTHONPATH=$HOME/icebin/pylib:$PYTHONPATH
+
+3. Run ``sh make_spackenv`` whenever your Spack installation changes (including right now).
+
+
+Giving Back
+-------------------
+
+If your software is publicly available, you should submit the
+``package.py`` for it as a pull request to the main Spack GitHub
+project.  This will ensure that anyone can install your software
+(almost) painlessly with a simple ``spack install`` command.  See here
+for how that has turned into detailed instructions that have
+successfully enabled collaborators to install complex software:
+
+   https://github.com/citibeth/icebin/blob/develop/README.rst

lib/spack/docs/index.rst

@@ -49,6 +49,7 @@ Table of Contents
    mirrors
    configuration
    developer_guide
+   case_studies
    command_index
    package_list
    API Docs <spack>

lib/spack/docs/packaging_guide.rst

@@ -401,10 +401,11 @@ the ``url`` declaration.  For example:
    :linenos:
 
    class Foo(Package):
+       version('8.2.1', '4136d7b4c04df68b686570afa26988ac')
+       ...
        def url_for_version(self, version):
            return 'http://example.com/version_%s/foo-%s.tar.gz' \
                % (version, version)
-       version('8.2.1', '4136d7b4c04df68b686570afa26988ac')
        ...
 
 If a URL cannot be derived systematically, you can add an explicit URL

lib/spack/spack/package.py

@@ -143,8 +143,10 @@ def install(self, spec, prefix):
       informational URL, so that users know what they're
       installing.
 
-    url
-      URL of the source archive that spack will fetch.
+    url or url_for_version(self, version)
+      If url, then the URL of the source archive that spack will fetch.
+      If url_for_version(), then a method returning the URL required
+      to fetch a particular version.
 
     install()
       This function tells spack how to build and install the