Merge pull request #19 in SCALE/spack from features/modules to develop

# By Todd Gamblin (4) and David Beckingsale (2)
# Via Todd Gamblin
* commit 'b601fd08caf21b5fc11e6998a5ebd20a04ac57ad':
  Bugfixes for csh environment modules.
  Bugfixes, more consolidation of modules code.
  Add csh/tcsh support for modules
  Consolidate most module code into spack.modules and spack.cmd.module
  Fixed up module support
  Added inital module support

11 files changed, 491 insertions, 173 deletions

diff --git a/lib/spack/spack/__init__.py b/lib/spack/spack/__init__.py
index 9eae4342e3..ab8978cecf 100644
--- a/lib/spack/spack/__init__.py
+++ b/lib/spack/spack/__init__.py
@@ -58,7 +58,6 @@ var_path       = join_path(prefix, "var", "spack")
 stage_path     = join_path(var_path, "stage")
 install_path   = join_path(prefix, "opt")
 share_path     = join_path(prefix, "share", "spack")
-dotkit_path    = join_path(share_path, "dotkit")
 
 #
 # Set up the packages database.
diff --git a/lib/spack/spack/cmd/dotkit.py b/lib/spack/spack/cmd/dotkit.py
deleted file mode 100644
index 7a691ae5c0..0000000000
--- a/lib/spack/spack/cmd/dotkit.py
+++ /dev/null
@@ -1,99 +0,0 @@
-##############################################################################
-# Copyright (c) 2013, Lawrence Livermore National Security, LLC.
-# Produced at the Lawrence Livermore National Laboratory.
-#
-# This file is part of Spack.
-# Written by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
-# LLNL-CODE-647188
-#
-# For details, see https://scalability-llnl.github.io/spack
-# Please also see the LICENSE file for our notice and the LGPL.
-#
-# This program 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) version 2.1 dated February 1999.
-#
-# This program 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 terms and
-# conditions of the GNU General Public License for more details.
-#
-# You should have received a copy of the GNU Lesser General Public License
-# along with this program; if not, write to the Free Software Foundation,
-# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
-##############################################################################
-import sys
-import os
-import shutil
-import argparse
-
-import llnl.util.tty as tty
-from llnl.util.lang import partition_list
-from llnl.util.filesystem import mkdirp
-
-import spack.cmd
-import spack.hooks.dotkit
-from spack.spec import Spec
-
-
-description ="Find dotkits for packages if they exist."
-
-def setup_parser(subparser):
-    subparser.add_argument(
-        '--refresh', action='store_true', help='Regenerate all dotkits')
-
-    subparser.add_argument(
-        'spec', nargs=argparse.REMAINDER, help='spec to find a dotkit for.')
-
-
-def dotkit_find(parser, args):
-    if not args.spec:
-        parser.parse_args(['dotkit', '-h'])
-
-    spec = spack.cmd.parse_specs(args.spec)
-    if len(spec) > 1:
-        tty.die("You can only pass one spec.")
-    spec = spec[0]
-
-    if not spack.db.exists(spec.name):
-        tty.die("No such package: %s" % spec.name)
-
-    specs = [s for s in spack.db.installed_package_specs() if s.satisfies(spec)]
-
-    if len(specs) == 0:
-        tty.die("No installed packages match spec %s" % spec)
-
-    if len(specs) > 1:
-        tty.error("Multiple matches for spec %s.  Choose one:" % spec)
-        for s in specs:
-            sys.stderr.write(s.tree(color=True))
-        sys.exit(1)
-
-    match = specs[0]
-    if not os.path.isfile(spack.hooks.dotkit.dotkit_file(match.package)):
-        tty.die("No dotkit is installed for package %s." % spec)
-
-    print match.format('$_$@$+$%@$=$#')
-
-
-def dotkit_refresh(parser, args):
-    query_specs = spack.cmd.parse_specs(args.spec)
-
-    specs = spack.db.installed_package_specs()
-    if query_specs:
-        specs = [s for s in specs
-                 if any(s.satisfies(q) for q in query_specs)]
-    else:
-        shutil.rmtree(spack.dotkit_path, ignore_errors=False)
-        mkdirp(spack.dotkit_path)
-
-    for spec in specs:
-        spack.hooks.dotkit.post_install(spec.package)
-
-
-
-def dotkit(parser, args):
-    if args.refresh:
-        dotkit_refresh(parser, args)
-    else:
-        dotkit_find(parser, args)
diff --git a/lib/spack/spack/cmd/load.py b/lib/spack/spack/cmd/load.py
new file mode 100644
index 0000000000..5bc6b15784
--- /dev/null
+++ b/lib/spack/spack/cmd/load.py
@@ -0,0 +1,38 @@
+##############################################################################
+# Copyright (c) 2013, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Written by David Beckingsale, david@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://scalability-llnl.github.io/spack
+# Please also see the LICENSE file for our notice and the LGPL.
+#
+# This program 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) version 2.1 dated February 1999.
+#
+# This program 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 terms and
+# conditions of the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+import argparse
+import spack.modules
+
+description ="Add package to environment using modules."
+
+def setup_parser(subparser):
+    """Parser is only constructed so that this prints a nice help
+       message with -h. """
+    subparser.add_argument(
+        'spec', nargs=argparse.REMAINDER, help='Spec of package to load with modules.')
+
+
+def load(parser, args):
+    spack.modules.print_help()
diff --git a/lib/spack/spack/cmd/module.py b/lib/spack/spack/cmd/module.py
new file mode 100644
index 0000000000..4f6de18532
--- /dev/null
+++ b/lib/spack/spack/cmd/module.py
@@ -0,0 +1,108 @@
+##############################################################################
+# Copyright (c) 2013, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Written by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://scalability-llnl.github.io/spack
+# Please also see the LICENSE file for our notice and the LGPL.
+#
+# This program 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) version 2.1 dated February 1999.
+#
+# This program 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 terms and
+# conditions of the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+import sys
+import os
+import shutil
+import argparse
+
+import llnl.util.tty as tty
+from llnl.util.lang import partition_list
+from llnl.util.filesystem import mkdirp
+
+import spack.cmd
+from spack.modules import module_types
+from spack.util.string import *
+
+from spack.spec import Spec
+
+description ="Manipulate modules and dotkits."
+
+
+def setup_parser(subparser):
+    sp = subparser.add_subparsers(metavar='SUBCOMMAND', dest='module_command')
+
+    refresh_parser = sp.add_parser('refresh', help='Regenerate all module files.')
+
+    find_parser = sp.add_parser('find', help='Find module files for packages.')
+    find_parser.add_argument(
+        'module_type', help="Type of module to find file for. [" + '|'.join(module_types) + "]")
+    find_parser.add_argument('spec', nargs='+', help='spec to find a module file for.')
+
+
+def module_find(mtype, spec_array):
+    """Look at all installed packages and see if the spec provided
+       matches any.  If it does, check whether there is a module file
+       of type <mtype> there, and print out the name that the user
+       should type to use that package's module.
+    """
+    specs = spack.cmd.parse_specs(spec_array)
+    if len(specs) > 1:
+        tty.die("You can only pass one spec.")
+    spec = specs[0]
+
+    if mtype not in module_types:
+        tty.die("Invalid module type: '%s'.  Options are " + comma_and(module_types))
+
+    specs = [s for s in spack.db.installed_package_specs() if s.satisfies(spec)]
+    if len(specs) == 0:
+        tty.die("No installed packages match spec %s" % spec)
+
+    if len(specs) > 1:
+        tty.error("Multiple matches for spec %s.  Choose one:" % spec)
+        for s in specs:
+            sys.stderr.write(s.tree(color=True))
+        sys.exit(1)
+
+    mt = module_types[mtype]
+    mod = mt(specs[0].package)
+    if not os.path.isfile(mod.file_name):
+        tty.error( mod.file_name)
+        tty.die("No %s module is installed for package %s." % (mtype, spec))
+
+    print mod.use_name
+
+
+def module_refresh():
+    """Regenerate all module files for installed packages known to
+       spack (some packages may no longer exist)."""
+    specs = [s for s in spack.db.installed_known_package_specs()]
+
+    for name, cls in module_types.items():
+        tty.msg("Regenerating %s module files." % name)
+        if os.path.isdir(cls.path):
+            shutil.rmtree(cls.path, ignore_errors=False)
+        mkdirp(cls.path)
+        for spec in specs:
+            tty.debug("   Writing file for %s." % spec)
+            cls(spec.package).write()
+
+
+
+def module(parser, args):
+    if args.module_command == 'refresh':
+        module_refresh()
+
+    elif args.module_command == 'find':
+        module_find(args.module_type, args.spec)
diff --git a/lib/spack/spack/cmd/unload.py b/lib/spack/spack/cmd/unload.py
new file mode 100644
index 0000000000..24e49b3f24
--- /dev/null
+++ b/lib/spack/spack/cmd/unload.py
@@ -0,0 +1,38 @@
+##############################################################################
+# Copyright (c) 2013, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Written by David Beckingsale, david@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://scalability-llnl.github.io/spack
+# Please also see the LICENSE file for our notice and the LGPL.
+#
+# This program 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) version 2.1 dated February 1999.
+#
+# This program 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 terms and
+# conditions of the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+import argparse
+import spack.modules
+
+description ="Remove package from environment using module."
+
+def setup_parser(subparser):
+    """Parser is only constructed so that this prints a nice help
+       message with -h. """
+    subparser.add_argument(
+        'spec', nargs=argparse.REMAINDER, help='Spec of package to unload with modules.')
+
+
+def unload(parser, args):
+    spack.modules.print_help()
diff --git a/lib/spack/spack/cmd/unuse.py b/lib/spack/spack/cmd/unuse.py
index a31e16d11a..7f0b384ea0 100644
--- a/lib/spack/spack/cmd/unuse.py
+++ b/lib/spack/spack/cmd/unuse.py
@@ -23,14 +23,16 @@
 # Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ##############################################################################
 import argparse
-import spack.cmd.use
+import spack.modules
 
 description ="Remove package from environment using dotkit."
 
 def setup_parser(subparser):
+    """Parser is only constructed so that this prints a nice help
+       message with -h. """
     subparser.add_argument(
-        'spec', nargs=argparse.REMAINDER, help='Spec of package to remove.')
+        'spec', nargs=argparse.REMAINDER, help='Spec of package to unuse with dotkit.')
 
 
 def unuse(parser, args):
-    spack.cmd.use.print_help()
+    spack.modules.print_help()
diff --git a/lib/spack/spack/cmd/use.py b/lib/spack/spack/cmd/use.py
index 10a0644df8..4990fea2f8 100644
--- a/lib/spack/spack/cmd/use.py
+++ b/lib/spack/spack/cmd/use.py
@@ -23,28 +23,16 @@
 # Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ##############################################################################
 import argparse
-import llnl.util.tty as tty
-import spack
+import spack.modules
 
 description ="Add package to environment using dotkit."
 
 def setup_parser(subparser):
+    """Parser is only constructed so that this prints a nice help
+       message with -h. """
     subparser.add_argument(
-        'spec', nargs=argparse.REMAINDER, help='Spec of package to add.')
-
-
-def print_help():
-    tty.msg("Spack dotkit support is not initialized.",
-            "",
-            "To use dotkit with Spack, you must first run the command",
-            "below, which you can copy and paste:",
-            "",
-            "For bash:",
-            "    . %s/setup-env.bash" % spack.share_path,
-            "",
-            "ksh/csh/tcsh shells are currently unsupported",
-            "")
+        'spec', nargs=argparse.REMAINDER, help='Spec of package to use with dotkit.')
 
 
 def use(parser, args):
-    print_help()
+    spack.modules.print_help()
diff --git a/lib/spack/spack/hooks/dotkit.py b/lib/spack/spack/hooks/dotkit.py
index 10b7732353..0f46f6a2fc 100644
--- a/lib/spack/spack/hooks/dotkit.py
+++ b/lib/spack/spack/hooks/dotkit.py
@@ -22,62 +22,14 @@
 # along with this program; if not, write to the Free Software Foundation,
 # Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ##############################################################################
-import os
-import re
-import textwrap
-import shutil
-from contextlib import closing
-
-from llnl.util.filesystem import join_path, mkdirp
-
-import spack
-
-
-def dotkit_file(pkg):
-    dk_file_name = pkg.spec.format('$_$@$%@$+$=$#') + ".dk"
-    return join_path(spack.dotkit_path, dk_file_name)
+import spack.modules
 
 
 def post_install(pkg):
-    if not os.path.exists(spack.dotkit_path):
-        mkdirp(spack.dotkit_path)
-
-    alterations = []
-    for var, path in [
-        ('PATH', pkg.prefix.bin),
-        ('MANPATH', pkg.prefix.man),
-        ('MANPATH', pkg.prefix.share_man),
-        ('LD_LIBRARY_PATH', pkg.prefix.lib),
-        ('LD_LIBRARY_PATH', pkg.prefix.lib64)]:
-
-        if os.path.isdir(path):
-            alterations.append("dk_alter %s %s\n" % (var, path))
-
-    if not alterations:
-        return
-
-    alterations.append("dk_alter CMAKE_PREFIX_PATH %s\n" % pkg.prefix)
-
-    dk_file = dotkit_file(pkg)
-    with closing(open(dk_file, 'w')) as dk:
-        # Put everything in the spack category.
-        dk.write('#c spack\n')
-
-        dk.write('#d %s\n' % pkg.spec.format("$_ $@"))
-
-        # Recycle the description
-        if pkg.__doc__:
-            doc = re.sub(r'\s+', ' ', pkg.__doc__)
-            for line in textwrap.wrap(doc, 72):
-                dk.write("#h %s\n" % line)
-
-        # Write alterations
-        for alter in alterations:
-            dk.write(alter)
+    dk = spack.modules.Dotkit(pkg)
+    dk.write()
 
 
 def post_uninstall(pkg):
-    dk_file = dotkit_file(pkg)
-    if os.path.exists(dk_file):
-        shutil.rmtree(dk_file, ignore_errors=True)
-
+    dk = spack.modules.Dotkit(pkg)
+    dk.remove()
diff --git a/lib/spack/spack/hooks/tclmodule.py b/lib/spack/spack/hooks/tclmodule.py
new file mode 100644
index 0000000000..d93da3177e
--- /dev/null
+++ b/lib/spack/spack/hooks/tclmodule.py
@@ -0,0 +1,35 @@
+##############################################################################
+# Copyright (c) 2013, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Written by David Beckingsale, david@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://scalability-llnl.github.io/spack
+# Please also see the LICENSE file for our notice and the LGPL.
+#
+# This program 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) version 2.1 dated February 1999.
+#
+# This program 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 terms and
+# conditions of the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+import spack.modules
+
+
+def post_install(pkg):
+    dk = spack.modules.TclModule(pkg)
+    dk.write()
+
+
+def post_uninstall(pkg):
+    dk = spack.modules.TclModule(pkg)
+    dk.remove()
diff --git a/lib/spack/spack/modules.py b/lib/spack/spack/modules.py
new file mode 100644
index 0000000000..3f56208f5b
--- /dev/null
+++ b/lib/spack/spack/modules.py
@@ -0,0 +1,247 @@
+##############################################################################
+# Copyright (c) 2013, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Written by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://scalability-llnl.github.io/spack
+# Please also see the LICENSE file for our notice and the LGPL.
+#
+# This program 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) version 2.1 dated February 1999.
+#
+# This program 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 terms and
+# conditions of the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+"""This module contains code for creating environment modules, which
+can include dotkits, tcl modules, lmod, and others.
+
+The various types of modules are installed by post-install hooks and
+removed after an uninstall by post-uninstall hooks.  This class
+consolidates the logic for creating an abstract description of the
+information that module systems need.  Currently that includes a
+number directories to be appended to paths in the user's environment:
+
+  * /bin directories to be appended to PATH
+  * /lib* directories for LD_LIBRARY_PATH
+  * /man* and /share/man* directories for LD_LIBRARY_PATH
+  * the package prefix for CMAKE_PREFIX_PATH
+
+This module also includes logic for coming up with unique names for
+the module files so that they can be found by the various
+shell-support files in $SPACK/share/spack/setup-env.*.
+
+Each hook in hooks/ implements the logic for writing its specific type
+of module file.
+"""
+__all__ = ['EnvModule', 'Dotkit', 'TclModule']
+
+import os
+import re
+import textwrap
+import shutil
+from contextlib import closing
+
+import llnl.util.tty as tty
+from llnl.util.filesystem import join_path, mkdirp
+
+import spack
+
+"""Registry of all types of modules.  Entries created by EnvModule's
+   metaclass."""
+module_types = {}
+
+
+def print_help():
+    """For use by commands to tell user how to activate shell support."""
+
+    tty.msg("Spack module/dotkit support is not initialized.",
+            "",
+            "To use dotkit or modules with Spack, you must first run",
+            "one of the commands below.  You can copy/paste them.",
+            "",
+            "For bash and zsh:",
+            "    . %s/setup-env.sh" % spack.share_path,
+            "",
+            "For csh and tcsh:",
+            "    setenv SPACK_ROOT %s"    % spack.prefix,
+            "    source %s/setup-env.csh" % spack.share_path,
+            "")
+
+
+class EnvModule(object):
+    name = 'env_module'
+
+    class __metaclass__(type):
+        def __init__(cls, name, bases, dict):
+            type.__init__(cls, name, bases, dict)
+            if cls.name != 'env_module':
+                module_types[cls.name] = cls
+
+
+    def __init__(self, pkg=None):
+        # category in the modules system
+        # TODO: come up with smarter category names.
+        self.category = "spack"
+
+        # Descriptions for the module system's UI
+        self.short_description = ""
+        self.long_description = ""
+
+        # dict pathname -> list of directories to be prepended to in
+        # the module file.
+        self._paths = None
+        self.pkg = pkg
+
+
+    @property
+    def paths(self):
+        if self._paths is None:
+            self._paths = {}
+
+            def add_path(path_name, directory):
+                path = self._paths.setdefault(path_name, [])
+                path.append(directory)
+
+            # Add paths if they exist.
+            for var, directory in [
+                    ('PATH', self.pkg.prefix.bin),
+                    ('MANPATH', self.pkg.prefix.man),
+                    ('MANPATH', self.pkg.prefix.share_man),
+                    ('LD_LIBRARY_PATH', self.pkg.prefix.lib),
+                    ('LD_LIBRARY_PATH', self.pkg.prefix.lib64)]:
+
+                if os.path.isdir(directory):
+                    add_path(var, directory)
+
+            # short description is just the package + version
+            # TODO: maybe packages can optionally provide it.
+            self.short_description = self.pkg.spec.format("$_ $@")
+
+            # long description is the docstring with reduced whitespace.
+            if self.pkg.__doc__:
+                self.long_description = re.sub(r'\s+', ' ', self.pkg.__doc__)
+
+        return self._paths
+
+
+    def write(self):
+        """Write out a module file for this object."""
+        module_dir = os.path.dirname(self.file_name)
+        if not os.path.exists(module_dir):
+            mkdirp(module_dir)
+
+        # If there are no paths, no need for a dotkit.
+        if not self.paths:
+            return
+
+        with closing(open(self.file_name, 'w')) as f:
+            self._write(f)
+
+
+    def _write(self, stream):
+        """To be implemented by subclasses."""
+        raise NotImplementedError()
+
+
+    @property
+    def file_name(self):
+        """Subclasses should implement this to return the name of the file
+           where this module lives."""
+        raise NotImplementedError()
+
+
+    @property
+    def use_name(self):
+        """Subclasses should implement this to return the name the
+           module command uses to refer to the package."""
+        raise NotImplementedError()
+
+
+    def remove(self):
+        mod_file = self.file_name
+        if os.path.exists(mod_file):
+            shutil.rmtree(mod_file, ignore_errors=True)
+
+
+class Dotkit(EnvModule):
+    name = 'dotkit'
+    path = join_path(spack.share_path, "dotkit")
+
+    @property
+    def file_name(self):
+        return join_path(Dotkit.path, self.pkg.spec.architecture,
+                         self.pkg.spec.format('$_$@$%@$+$#.dk'))
+
+    @property
+    def use_name(self):
+        return self.pkg.spec.format('$_$@$%@$+$#')
+
+
+    def _write(self, dk_file):
+        # Category
+        if self.category:
+            dk_file.write('#c %s\n' % self.category)
+
+        # Short description
+        if self.short_description:
+            dk_file.write('#d %s\n' % self.short_description)
+
+        # Long description
+        if self.long_description:
+            for line in textwrap.wrap(self.long_description, 72):
+                dk_file.write("#h %s\n" % line)
+
+        # Path alterations
+        for var, dirs in self.paths.items():
+            for directory in dirs:
+                dk_file.write("dk_alter %s %s\n" % (var, directory))
+
+        # Let CMake find this package.
+        dk_file.write("dk_alter CMAKE_PREFIX_PATH %s\n" % self.pkg.prefix)
+
+
+class TclModule(EnvModule):
+    name = 'tcl'
+    path = join_path(spack.share_path, "modules")
+
+    @property
+    def file_name(self):
+        return join_path(TclModule.path, self.pkg.spec.architecture, self.use_name)
+
+
+    @property
+    def use_name(self):
+        return self.pkg.spec.format('$_$@$%@$+$#')
+
+
+    def _write(self, m_file):
+        # TODO: cateogry?
+        m_file.write('#%Module1.0\n')
+
+        # Short description
+        if self.short_description:
+            m_file.write('module-whatis \"%s\"\n\n' % self.short_description)
+
+        # Long description
+        if self.long_description:
+            m_file.write('proc ModulesHelp { } {\n')
+            doc = re.sub(r'"', '\"', self.long_description)
+            m_file.write("puts stderr \"%s\"\n" % doc)
+            m_file.write('}\n\n')
+
+        # Path alterations
+        for var, dirs in self.paths.items():
+            for directory in dirs:
+                m_file.write("prepend-path %s \"%s\"\n" % (var, directory))
+
+        m_file.write("prepend-path CMAKE_PREFIX_PATH \"%s\"\n" % self.pkg.prefix)
diff --git a/lib/spack/spack/packages.py b/lib/spack/spack/packages.py
index ba997bf269..fd75d8e326 100644
--- a/lib/spack/spack/packages.py
+++ b/lib/spack/spack/packages.py
@@ -124,6 +124,16 @@ class PackageDB(object):
         return installed
 
 
+    def installed_known_package_specs(self):
+        """Read installed package names straight from the install
+           directory layout, but return only specs for which the
+           package is known to this version of spack.
+        """
+        for spec in spack.install_layout.all_specs():
+            if self.exists(spec.name):
+                yield spec
+
+
     @memoized
     def all_package_names(self):
         """Generator function for all packages.  This looks for