init: move spack.repo global variable into its own module

- spack.repository module is now spack.repo

- `spack.repo` is now `spack.repo.path()` and loaded lazily

- Added `spack.repo.get()` and `spack.repo.all_package_names()` as
  convenience functions to simplify the new lazy interface.

- updated tests and code

lib/spack/docs/repositories.rst

@@ -445,7 +445,7 @@ Spack repo namespaces are actually Python namespaces tacked on under
 ``spack.pkg``.  The search semantics of ``repos.yaml`` are actually
 implemented using Python's built-in `sys.path
 <https://docs.python.org/2/library/sys.html#sys.path>`_ search.  The
-:py:mod:`spack.repository` module implements a custom `Python importer
+:py:mod:`spack.repo` module implements a custom `Python importer
 <https://docs.python.org/2/library/imp.html>`_.
 
 .. warning::

lib/spack/spack/__init__.py

@@ -23,7 +23,6 @@
 # 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
 
 #: major, minor, patch version for Spack, in a tuple
 spack_version_info = (0, 11, 2)
@@ -32,29 +31,9 @@
 spack_version = '.'.join(str(v) for v in spack_version_info)
 
 
-# Set up the default packages database.
-import spack.error
-try:
-    import spack.repository
-    repo = spack.repository.RepoPath()
-    sys.meta_path.append(repo)
-except spack.error.SpackError as e:
-    import llnl.util.tty as tty
-    tty.die('while initializing Spack RepoPath:', e.message)
-
-
 #-----------------------------------------------------------------------------
 # When packages call 'from spack import *', we import a set of things that
 # should be useful for builds.
-#
-# Spack internal code should call 'import spack' and accesses other
-# variables (spack.repo, paths, etc.) directly.
-#
-# TODO: maybe this should be separated out to build_environment.py?
-# TODO: it's not clear where all the stuff that needs to be included in
-#       packages should live.  This file is overloaded for spack core vs.
-#       for packages.
-#
 #-----------------------------------------------------------------------------
 __all__ = []
 

lib/spack/spack/build_environment.py

@@ -587,8 +587,8 @@ def setup_package(pkg, dirty):
     for dspec in pkg.spec.traverse(order='post', root=False,
                                    deptype=('build', 'test')):
         # If a user makes their own package repo, e.g.
-        # spack.repos.mystuff.libelf.Libelf, and they inherit from
-        # an existing class like spack.repos.original.libelf.Libelf,
+        # spack.pkg.mystuff.libelf.Libelf, and they inherit from
+        # an existing class like spack.pkg.original.libelf.Libelf,
         # then set the module variables for both classes so the
         # parent class can still use them if it gets called.
         spkg = dspec.package

lib/spack/spack/cmd/blame.py

@@ -31,6 +31,7 @@
 from llnl.util.tty.colify import colify_table
 
 import spack.paths
+import spack.repo
 from spack.util.executable import which
 from spack.cmd import spack_is_git_repo
 

lib/spack/spack/cmd/bootstrap.py

@@ -23,7 +23,8 @@
 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ##############################################################################
 import llnl.util.tty as tty
-import spack
+
+import spack.repo
 import spack.cmd
 import spack.cmd.common.arguments as arguments
 

lib/spack/spack/cmd/buildcache.py

@@ -26,8 +26,10 @@
 
 import llnl.util.tty as tty
 
-import spack
 import spack.cmd
+import spack.repo
+import spack.store
+import spack.spec
 import spack.binary_distribution as bindist
 
 description = "create, download and install binary packages"

lib/spack/spack/cmd/checksum.py

@@ -27,8 +27,9 @@
 import argparse
 
 import llnl.util.tty as tty
-import spack
+
 import spack.cmd
+import spack.repo
 import spack.util.crypto
 import spack.util.web
 from spack.util.naming import valid_fully_qualified_module_name

lib/spack/spack/cmd/clean.py

@@ -26,9 +26,10 @@
 
 import llnl.util.tty as tty
 
-import spack
 import spack.caches
 import spack.cmd
+import spack.repo
+import spack.stage
 
 description = "remove temporary build files and/or downloaded archives"
 section = "build"

lib/spack/spack/cmd/create.py

@@ -32,7 +32,7 @@
 import spack.cmd
 import spack.util.web
 from llnl.util.filesystem import mkdirp
-from spack.repository import Repo
+import spack.repo
 from spack.spec import Spec
 from spack.util.executable import which, ProcessError
 from spack.util.naming import mod_to_class
@@ -648,17 +648,17 @@ def get_repository(args, name):
     # Figure out where the new package should live
     repo_path = args.repo
     if repo_path is not None:
-        repo = Repo(repo_path)
+        repo = spack.repo.Repo(repo_path)
         if spec.namespace and spec.namespace != repo.namespace:
             tty.die("Can't create package with namespace {0} in repo with "
                     "namespace {1}".format(spec.namespace, repo.namespace))
     else:
         if spec.namespace:
-            repo = spack.repo.get_repo(spec.namespace, None)
+            repo = spack.repo.path().get_repo(spec.namespace, None)
             if not repo:
                 tty.die("Unknown namespace: '{0}'".format(spec.namespace))
         else:
-            repo = spack.repo.first_repo()
+            repo = spack.repo.path().first_repo()
 
     # Set the namespace on the spec if it's not there already
     if not spec.namespace:

lib/spack/spack/cmd/dependencies.py

@@ -27,8 +27,8 @@
 import llnl.util.tty as tty
 from llnl.util.tty.colify import colify
 
-import spack
 import spack.store
+import spack.repo
 import spack.cmd
 
 description = "show dependencies of a package"
@@ -73,8 +73,9 @@ def dependencies(parser, args):
         if not spec.virtual:
             packages = [spec.package]
         else:
-            packages = [spack.repo.get(s.name)
-                        for s in spack.repo.providers_for(spec)]
+            packages = [
+                spack.repo.get(s.name)
+                for s in spack.repo.path().providers_for(spec)]
 
         dependencies = set()
         for pkg in packages:

lib/spack/spack/cmd/dependents.py

@@ -27,7 +27,7 @@
 import llnl.util.tty as tty
 from llnl.util.tty.colify import colify
 
-import spack
+import spack.repo
 import spack.store
 import spack.cmd
 
@@ -57,14 +57,14 @@ def inverted_dependencies():
        actual dependents.
     """
     dag = {}
-    for pkg in spack.repo.all_packages():
+    for pkg in spack.repo.path().all_packages():
         dag.setdefault(pkg.name, set())
         for dep in pkg.dependencies:
             deps = [dep]
 
             # expand virtuals if necessary
-            if spack.repo.is_virtual(dep):
-                deps += [s.name for s in spack.repo.providers_for(dep)]
+            if spack.repo.path().is_virtual(dep):
+                deps += [s.name for s in spack.repo.path().providers_for(dep)]
 
             for d in deps:
                 dag.setdefault(d, set()).add(pkg.name)

lib/spack/spack/cmd/diy.py

@@ -28,9 +28,9 @@
 
 import llnl.util.tty as tty
 
-import spack
 import spack.config
 import spack.cmd
+import spack.repo
 import spack.cmd.common.arguments as arguments
 from spack.stage import DIYStage
 
@@ -78,7 +78,7 @@ def diy(self, args):
         tty.die("spack diy only takes one spec.")
 
     spec = specs[0]
-    if not spack.repo.exists(spec.name):
+    if not spack.repo.path().exists(spec.name):
         tty.die("No package for '{0}' was found.".format(spec.name),
                 "  Use `spack create` to create a new package")
 

lib/spack/spack/cmd/edit.py

@@ -29,8 +29,8 @@
 
 import spack.cmd
 import spack.paths
+import spack.repo
 from spack.spec import Spec
-from spack.repository import Repo
 from spack.util.editor import editor
 
 description = "open package files in $EDITOR"
@@ -48,11 +48,11 @@ def edit_package(name, repo_path, namespace):
     """
     # Find the location of the package
     if repo_path:
-        repo = Repo(repo_path)
+        repo = spack.repo.Repo(repo_path)
     elif namespace:
-        repo = spack.repo.get_repo(namespace)
+        repo = spack.repo.path().get_repo(namespace)
     else:
-        repo = spack.repo
+        repo = spack.repo.path()
     path = repo.filename_for_package_name(name)
 
     spec = Spec(name)

lib/spack/spack/cmd/extensions.py

@@ -27,9 +27,9 @@
 import llnl.util.tty as tty
 from llnl.util.tty.colify import colify
 
-import spack
 import spack.cmd
 import spack.cmd.find
+import spack.repo
 import spack.store
 from spack.directory_layout import YamlViewExtensionsLayout
 
@@ -105,7 +105,7 @@ def extensions(parser, args):
     if show_packages:
         #
         # List package names of extensions
-        extensions = spack.repo.extensions_for(spec)
+        extensions = spack.repo.path().extensions_for(spec)
         if not extensions:
             tty.msg("%s has no extensions." % spec.cshort_spec)
         else:

lib/spack/spack/cmd/fetch.py

@@ -26,8 +26,9 @@
 
 import llnl.util.tty as tty
 
-import spack
 import spack.cmd
+import spack.config
+import spack.repo
 import spack.cmd.common.arguments as arguments
 
 description = "fetch archives for packages"

lib/spack/spack/cmd/find.py

@@ -26,8 +26,8 @@
 
 import llnl.util.tty as tty
 import llnl.util.lang
-import spack
-import spack.database
+
+import spack.repo
 import spack.cmd.common.arguments as arguments
 from spack.cmd import display_specs
 
@@ -147,7 +147,7 @@ def find(parser, args):
 
     # If tags have been specified on the command line, filter by tags
     if args.tags:
-        packages_with_tags = spack.repo.packages_with_tags(*args.tags)
+        packages_with_tags = spack.repo.path().packages_with_tags(*args.tags)
         query_specs = [x for x in query_specs if x.name in packages_with_tags]
 
     # Display the result

lib/spack/spack/cmd/info.py

@@ -25,15 +25,15 @@
 from __future__ import print_function
 
 import textwrap
-
 from six.moves import zip_longest
 
+import llnl.util.tty.color as color
 from llnl.util.tty.colify import colify
 
-import llnl.util.tty.color as color
-import spack
-import spack.fetch_strategy as fs
+import spack.repo
 import spack.spec
+import spack.fetch_strategy as fs
+
 
 description = 'get detailed information on a particular package'
 section = 'basic'

lib/spack/spack/cmd/list.py

@@ -37,7 +37,8 @@
 import llnl.util.tty as tty
 from llnl.util.tty.colify import colify
 
-import spack
+import spack.dependency
+import spack.repo
 import spack.cmd.common.arguments as arguments
 
 description = "list and search available packages"
@@ -184,7 +185,7 @@ def rst(pkg_names):
                                    reversed(sorted(pkg.versions))))
             print()
 
-        for deptype in spack.all_deptypes:
+        for deptype in spack.dependency.all_deptypes:
             deps = pkg.dependencies_of_type(deptype)
             if deps:
                 print('%s Dependencies' % deptype.capitalize())
@@ -272,7 +273,7 @@ def head(n, span_id, title, anchor=None):
             print(', '.join(str(v) for v in reversed(sorted(pkg.versions))))
             print('</dd>')
 
-        for deptype in spack.all_deptypes:
+        for deptype in spack.dependency.all_deptypes:
             deps = pkg.dependencies_of_type(deptype)
             if deps:
                 print('<dt>%s Dependencies:</dt>' % deptype.capitalize())
@@ -301,7 +302,8 @@ def list(parser, args):
 
     # Filter by tags
     if args.tags:
-        packages_with_tags = set(spack.repo.packages_with_tags(*args.tags))
+        packages_with_tags = set(
+            spack.repo.path().packages_with_tags(*args.tags))
         sorted_packages = set(sorted_packages) & packages_with_tags
         sorted_packages = sorted(sorted_packages)
 

lib/spack/spack/cmd/location.py

@@ -29,6 +29,7 @@
 
 import spack.paths
 import spack.cmd
+import spack.repo
 
 description = "print out locations of various directories used by Spack"
 section = "environment"
@@ -79,7 +80,7 @@ def location(parser, args):
         print(spack.paths.prefix)
 
     elif args.packages:
-        print(spack.repo.first_repo().root)
+        print(spack.repo.path().first_repo().root)
 
     elif args.stages:
         print(spack.paths.stage_path)
@@ -101,7 +102,7 @@ def location(parser, args):
 
             if args.package_dir:
                 # This one just needs the spec name.
-                print(spack.repo.dirname_for_package_name(spec.name))
+                print(spack.repo.path().dirname_for_package_name(spec.name))
 
             else:
                 # These versions need concretized specs.

lib/spack/spack/cmd/mirror.py

@@ -29,11 +29,11 @@
 import llnl.util.tty as tty
 from llnl.util.tty.colify import colify
 
-import spack
 import spack.cmd
 import spack.concretize
 import spack.config
 import spack.mirror
+import spack.repo
 import spack.cmd.common.arguments as arguments
 from spack.spec import Spec
 from spack.error import SpackError

lib/spack/spack/cmd/module.py

@@ -27,10 +27,12 @@
 import collections
 import os
 import shutil
-import spack.modules
+
+from llnl.util import filesystem, tty
 
 import spack.cmd
-from llnl.util import filesystem, tty
+import spack.modules
+import spack.repo
 from spack.cmd.common import arguments
 
 description = "manipulate module files"
@@ -278,9 +280,10 @@ def refresh(module_types, specs, args):
 
         cls = spack.modules.module_types[module_type]
 
+        # skip unknown packages.
         writers = [
-            cls(spec) for spec in specs if spack.repo.exists(spec.name)
-        ]  # skip unknown packages.
+            cls(spec) for spec in specs
+            if spack.repo.path().exists(spec.name)]
 
         # Filter blacklisted packages early
         writers = [x for x in writers if not x.conf.blacklisted]

lib/spack/spack/cmd/patch.py

@@ -26,7 +26,7 @@
 
 import llnl.util.tty as tty
 
-import spack
+import spack.repo
 import spack.cmd
 import spack.cmd.common.arguments as arguments
 

lib/spack/spack/cmd/pkg.py

@@ -25,13 +25,14 @@
 from __future__ import print_function
 
 import os
-
 import argparse
+
 import llnl.util.tty as tty
 from llnl.util.tty.colify import colify
 from llnl.util.filesystem import working_dir
 
 import spack.paths
+import spack.repo
 from spack.util.executable import which
 from spack.cmd import spack_is_git_repo
 
@@ -90,7 +91,7 @@ def list_packages(rev):
 
 def pkg_add(args):
     for pkg_name in args.packages:
-        filename = spack.repo.filename_for_package_name(pkg_name)
+        filename = spack.repo.path().filename_for_package_name(pkg_name)
         if not os.path.isfile(filename):
             tty.die("No such package: %s.  Path does not exist:" %
                     pkg_name, filename)

lib/spack/spack/cmd/providers.py

@@ -27,8 +27,8 @@
 
 import llnl.util.tty.colify as colify
 
-import spack
 import spack.cmd
+import spack.repo
 
 description = "list packages that provide a particular virtual package"
 section = "basic"
@@ -46,7 +46,7 @@ def setup_parser(subparser):
 
 
 def providers(parser, args):
-    valid_virtuals = sorted(spack.repo.provider_index.providers.keys())
+    valid_virtuals = sorted(spack.repo.path().provider_index.providers.keys())
 
     buffer = six.StringIO()
     isatty = sys.stdout.isatty()
@@ -77,5 +77,5 @@ def providers(parser, args):
     for spec in specs:
         if sys.stdout.isatty():
             print("{0}:".format(spec))
-        spack.cmd.display_specs(sorted(spack.repo.providers_for(spec)))
+        spack.cmd.display_specs(sorted(spack.repo.path().providers_for(spec)))
         print('')

lib/spack/spack/cmd/repo.py

@@ -30,7 +30,7 @@
 
 import spack.spec
 import spack.config
-from spack.repository import Repo, create_repo, canonicalize_path, RepoError
+from spack.repo import Repo, create_repo, canonicalize_path, RepoError
 
 description = "manage package source repositories"
 section = "config"

lib/spack/spack/cmd/restage.py

@@ -26,8 +26,8 @@
 
 import llnl.util.tty as tty
 
-import spack
 import spack.cmd
+import spack.repo
 
 description = "revert checked out package source code"
 section = "build"

lib/spack/spack/cmd/setup.py

@@ -29,13 +29,15 @@
 import sys
 
 import llnl.util.tty as tty
-import spack
+from llnl.util.filesystem import set_executable
+
+import spack.repo
 import spack.store
 import spack.cmd
 import spack.cmd.install as install
 import spack.cmd.common.arguments as arguments
-from llnl.util.filesystem import set_executable
-from spack import which
+from spack.util.executable import which
+
 from spack.stage import DIYStage
 
 description = "create a configuration script and module, but don't build"
@@ -135,7 +137,7 @@ def setup(self, args):
     # Take a write lock before checking for existence.
     with spack.store.db.write_transaction():
         spec = specs[0]
-        if not spack.repo.exists(spec.name):
+        if not spack.repo.path().exists(spec.name):
             tty.die("No package for '{0}' was found.".format(spec.name),
                     "  Use `spack create` to create a new package")
         if not spec.versions.concrete:

lib/spack/spack/cmd/stage.py

@@ -26,7 +26,7 @@
 
 import llnl.util.tty as tty
 
-import spack
+import spack.repo
 import spack.cmd
 import spack.cmd.common.arguments as arguments
 

lib/spack/spack/cmd/uninstall.py

@@ -29,7 +29,7 @@
 import spack
 import spack.cmd
 import spack.store
-import spack.repository
+import spack.repo
 
 from llnl.util import tty
 
@@ -149,7 +149,7 @@ def do_uninstall(specs, force):
         try:
             # should work if package is known to spack
             packages.append(item.package)
-        except spack.repository.UnknownEntityError:
+        except spack.repo.UnknownEntityError:
             # The package.py file has gone away -- but still
             # want to uninstall.
             spack.Package.uninstall_by_spec(item, force=True)

lib/spack/spack/cmd/url.py

@@ -26,7 +26,7 @@
 
 from collections import defaultdict
 
-import spack
+import spack.repo
 
 from llnl.util import tty
 from spack.url import parse_version_offset, parse_name_offset
@@ -144,7 +144,7 @@ def url_list(args):
     urls = set()
 
     # Gather set of URLs from all packages
-    for pkg in spack.repo.all_packages():
+    for pkg in spack.repo.path().all_packages():
         url = getattr(pkg.__class__, 'url', None)
         urls = url_list_parsing(args, urls, url, pkg)
 
@@ -178,7 +178,7 @@ def url_summary(args):
     tty.msg('Generating a summary of URL parsing in Spack...')
 
     # Loop through all packages
-    for pkg in spack.repo.all_packages():
+    for pkg in spack.repo.path().all_packages():
         urls = set()
 
         url = getattr(pkg.__class__, 'url', None)

lib/spack/spack/cmd/versions.py

@@ -26,7 +26,8 @@
 
 from llnl.util.tty.colify import colify
 import llnl.util.tty as tty
-import spack
+
+import spack.repo
 
 description = "list available versions of a package"
 section = "packaging"

lib/spack/spack/concretize.py

@@ -39,7 +39,7 @@
 from contextlib import contextmanager
 from six import iteritems
 
-import spack
+import spack.repo
 import spack.abi
 import spack.spec
 import spack.compilers
@@ -102,7 +102,7 @@ def _valid_virtuals_and_externals(self, spec):
         pref_key = lambda spec: 0  # no-op pref key
 
         if spec.virtual:
-            candidates = spack.repo.providers_for(spec)
+            candidates = spack.repo.path().providers_for(spec)
             if not candidates:
                 raise spack.spec.UnsatisfiableProviderSpecError(
                     candidates[0], spec)

lib/spack/spack/database.py

@@ -55,7 +55,7 @@
 from llnl.util.lock import Lock, WriteTransaction, ReadTransaction
 
 import spack.store
-import spack.repository
+import spack.repo
 import spack.spec
 import spack.util.spack_yaml as syaml
 import spack.util.spack_json as sjson
@@ -903,7 +903,7 @@ def query(
                 if explicit is not any and rec.explicit != explicit:
                     continue
 
-                if known is not any and spack.repo.exists(
+                if known is not any and spack.repo.path().exists(
                         rec.spec.name) != known:
                     continue
 

lib/spack/spack/main.py

@@ -43,6 +43,8 @@
 import spack
 import spack.config
 import spack.paths
+import spack.repo
+import spack.util.debug
 from spack.error import SpackError
 
 
@@ -347,13 +349,12 @@ def setup_main_options(args):
     tty.set_stacktrace(args.stacktrace)
 
     if args.debug:
-        import spack.util.debug as debug
-        debug.register_interrupt_handler()
+        spack.util.debug.register_interrupt_handler()
         spack.config.set('config:debug', True, scope='command_line')
 
     if args.mock:
-        from spack.repository import RepoPath
-        spack.repo.swap(RepoPath(spack.paths.mock_packages_path))
+        rp = spack.repo.RepoPath(spack.paths.mock_packages_path)
+        spack.repo.set_path(rp)
 
     # If the user asked for it, don't check ssl certs.
     if args.insecure:

lib/spack/spack/package.py

@@ -53,7 +53,6 @@
 
 import llnl.util.tty as tty
 
-import spack
 import spack.config
 import spack.paths
 import spack.store
@@ -64,7 +63,7 @@
 import spack.hooks
 import spack.mirror
 import spack.mixins
-import spack.repository
+import spack.repo
 import spack.url
 import spack.util.web
 import spack.multimethod
@@ -662,9 +661,9 @@ def possible_dependencies(
             visited = set([self.name])
 
         for i, name in enumerate(self.dependencies):
-            if spack.repo.is_virtual(name):
+            if spack.repo.path().is_virtual(name):
                 if expand_virtuals:
-                    providers = spack.repo.providers_for(name)
+                    providers = spack.repo.path().providers_for(name)
                     dep_names = [spec.name for spec in providers]
                 else:
                     visited.add(name)
@@ -1934,7 +1933,7 @@ def uninstall_by_spec(spec, force=False):
         # Try to get the pcakage for the spec
         try:
             pkg = spec.package
-        except spack.repository.UnknownEntityError:
+        except spack.repo.UnknownEntityError:
             pkg = None
 
         # Pre-uninstall hook runs first.
@@ -2313,25 +2312,25 @@ def dump_packages(spec, path):
 
             # Create a source repo and get the pkg directory out of it.
             try:
-                source_repo = spack.repository.Repo(source_repo_root)
+                source_repo = spack.repo.Repo(source_repo_root)
                 source_pkg_dir = source_repo.dirname_for_package_name(
                     node.name)
-            except spack.repository.RepoError:
+            except spack.repo.RepoError:
                 tty.warn("Warning: Couldn't copy in provenance for %s" %
                          node.name)
 
         # Create a destination repository
         dest_repo_root = join_path(path, node.namespace)
         if not os.path.exists(dest_repo_root):
-            spack.repository.create_repo(dest_repo_root)
-        repo = spack.repository.Repo(dest_repo_root)
+            spack.repo.create_repo(dest_repo_root)
+        repo = spack.repo.Repo(dest_repo_root)
 
         # Get the location of the package in the dest repo.
         dest_pkg_dir = repo.dirname_for_package_name(node.name)
         if node is not spec:
             install_tree(source_pkg_dir, dest_pkg_dir)
         else:
-            spack.repo.dump_provenance(node, dest_pkg_dir)
+            spack.repo.path().dump_provenance(node, dest_pkg_dir)
 
 
 def print_pkg(message):

lib/spack/spack/package_prefs.py

@@ -27,7 +27,7 @@
 
 from llnl.util.lang import classproperty
 
-import spack
+import spack.repo
 import spack.error
 from spack.util.path import canonicalize_path
 from spack.version import VersionList
@@ -51,7 +51,7 @@ def get_packages_config():
     # by sometihng, not just packages/names that don't exist.
     # So, this won't include, e.g., 'all'.
     virtuals = [(pkg_name, pkg_name._start_mark) for pkg_name in config
-                if spack.repo.is_virtual(pkg_name)]
+                if spack.repo.path().is_virtual(pkg_name)]
 
     # die if there are virtuals in `packages.py`
     if virtuals:

lib/spack/spack/relocate.py

@@ -26,7 +26,7 @@
 import os
 import platform
 import re
-import spack
+import spack.repo
 import spack.cmd
 from spack.util.executable import Executable, ProcessError
 from llnl.util.filesystem import filter_file

lib/spack/spack/repo.py

@@ -33,6 +33,8 @@
 import re
 import traceback
 import json
+from contextlib import contextmanager
+from six import string_types
 
 try:
     from collections.abc import Mapping
@@ -222,8 +224,7 @@ def update_package(self, pkg_name):
             pkg_name (str): name of the package to be removed from the index
 
         """
-
-        package = spack.repo.get(pkg_name)
+        package = path().get(pkg_name)
 
         # Remove the package from the list of packages, if present
         for pkg_list in self._tag_dict.values():
@@ -345,13 +346,19 @@ def make_tag_index_cache(packages_path, namespace):
 class RepoPath(object):
     """A RepoPath is a list of repos that function as one.
 
-       It functions exactly like a Repo, but it operates on the
-       combined results of the Repos in its list instead of on a
-       single package repository.
+    It functions exactly like a Repo, but it operates on the combined
+    results of the Repos in its list instead of on a single package
+    repository.
+
+    Args:
+        repos (list): list Repo objects or paths to put in this RepoPath
+
+    Optional Args:
+        repo_namespace (str): super-namespace for all packages in this
+            RepoPath (used when importing repos as modules)
     """
 
-    def __init__(self, *repo_dirs, **kwargs):
-        # super-namespace for all packages in the RepoPath
+    def __init__(self, *repos, **kwargs):
         self.super_namespace = kwargs.get('namespace', repo_namespace)
 
         self.repos = []
@@ -361,41 +368,17 @@ def __init__(self, *repo_dirs, **kwargs):
         self._all_package_names = None
         self._provider_index = None
 
-        # If repo_dirs is empty, just use the configuration
-        if not repo_dirs:
-            import spack.config
-            repo_dirs = spack.config.get('repos')
-            if not repo_dirs:
-                raise NoRepoConfiguredError(
-                    "Spack configuration contains no package repositories.")
-
         # Add each repo to this path.
-        for root in repo_dirs:
+        for repo in repos:
             try:
-                repo = Repo(root, self.super_namespace)
+                if isinstance(repo, string_types):
+                    repo = Repo(repo, self.super_namespace)
                 self.put_last(repo)
             except RepoError as e:
-                tty.warn("Failed to initialize repository at '%s'." % root,
+                tty.warn("Failed to initialize repository: '%s'." % repo,
                          e.message,
                          "To remove the bad repository, run this command:",
-                         "    spack repo rm %s" % root)
-
-    def swap(self, other):
-        """Convenience function to make swapping repositories easier.
-
-        This is currently used by mock tests.
-        TODO: Maybe there is a cleaner way.
-
-        """
-        attrs = ['repos',
-                 'by_namespace',
-                 'by_path',
-                 '_all_package_names',
-                 '_provider_index']
-        for attr in attrs:
-            tmp = getattr(self, attr)
-            setattr(self, attr, getattr(other, attr))
-            setattr(other, attr, tmp)
+                         "    spack repo rm %s" % repo)
 
     def _add(self, repo):
         """Add a repository to the namespace and path indexes.
@@ -1096,6 +1079,70 @@ def create_repo(root, namespace=None):
     return full_path, namespace
 
 
+#: Singleton repo path instance
+_path = None
+
+
+def set_path(repo):
+    """Set the path() singleton to a specific value.
+
+    Overwrite _path and register it as an importer in sys.meta_path if
+    it is a ``Repo`` or ``RepoPath``.
+    """
+    global _path
+    _path = repo
+
+    # make the new repo_path an importer if needed
+    append = isinstance(repo, (Repo, RepoPath))
+    if append:
+        sys.meta_path.append(_path)
+    return append
+
+
+def path():
+    """Get the singleton RepoPath instance for Spack.
+
+    Create a RepoPath, add it to sys.meta_path, and return it.
+
+    TODO: consider not making this a singleton.
+    """
+    if _path is None:
+        repo_dirs = spack.config.get('repos')
+        if not repo_dirs:
+            raise NoRepoConfiguredError(
+                "Spack configuration contains no package repositories.")
+        set_path(RepoPath(*repo_dirs))
+
+    return _path
+
+
+def get(spec):
+    """Convenience wrapper around ``spack.repo.get()``."""
+    return path().get(spec)
+
+
+def all_package_names():
+    """Convenience wrapper around ``spack.repo.all_package_names()``."""
+    return path().all_package_names()
+
+
+@contextmanager
+def swap(repo_path):
+    """Temporarily use another RepoPath."""
+    global _path
+
+    # swap out _path for repo_path
+    saved = _path
+    remove_from_meta = set_path(repo_path)
+
+    yield
+
+    # restore _path and sys.meta_path
+    if remove_from_meta:
+        sys.meta_path.remove(repo_path)
+    _path = saved
+
+
 class RepoError(spack.error.SpackError):
     """Superclass for repository-related errors."""
 

lib/spack/spack/spec.py

@@ -114,12 +114,11 @@
 from llnl.util.lang import check_kwargs
 from llnl.util.tty.color import cwrite, colorize, cescape, get_color_when
 
-import spack
-
 import spack.architecture
 import spack.compilers as compilers
 import spack.error
 import spack.parse
+import spack.repo
 import spack.store
 import spack.util.spack_json as sjson
 import spack.util.spack_yaml as syaml
@@ -1229,7 +1228,7 @@ def package_class(self):
         """Internal package call gets only the class object for a package.
            Use this to just get package metadata.
         """
-        return spack.repo.get_pkg_class(self.fullname)
+        return spack.repo.path().get_pkg_class(self.fullname)
 
     @property
     def virtual(self):
@@ -1245,7 +1244,7 @@ def virtual(self):
     @staticmethod
     def is_virtual(name):
         """Test if a name is virtual without requiring a Spec."""
-        return (name is not None) and (not spack.repo.exists(name))
+        return (name is not None) and (not spack.repo.path().exists(name))
 
     @property
     def concrete(self):
@@ -1850,7 +1849,7 @@ def concretize(self, tests=False):
             # we can do it as late as possible to allow as much
             # compatibility across repositories as possible.
             if s.namespace is None:
-                s.namespace = spack.repo.repo_for_pkg(s.name).namespace
+                s.namespace = spack.repo.path().repo_for_pkg(s.name).namespace
 
             if s.concrete:
                 continue
@@ -2456,7 +2455,7 @@ def satisfies(self, other, deps=True, strict=False, strict_deps=False):
         if not self.virtual and other.virtual:
             try:
                 pkg = spack.repo.get(self.fullname)
-            except spack.repository.UnknownEntityError:
+            except spack.repo.UnknownEntityError:
                 # If we can't get package info on this spec, don't treat
                 # it as a provider of this vdep.
                 return False

lib/spack/spack/test/build_systems.py

@@ -26,6 +26,7 @@
 import spack
 import pytest
 
+import spack.repo
 from spack.build_environment import get_std_cmake_args
 from spack.spec import Spec
 

lib/spack/spack/test/cmd/flake8.py

@@ -31,7 +31,7 @@
 
 import spack.paths
 from spack.cmd.flake8 import flake8, setup_parser, changed_files
-from spack.repository import Repo
+from spack.repo import Repo
 from spack.util.executable import which
 
 

lib/spack/spack/test/cmd/install.py

@@ -165,8 +165,8 @@ def test_install_output_on_build_error(mock_packages, mock_archive, mock_fetch,
 
 
 @pytest.mark.disable_clean_stage_check
-def test_install_output_on_python_error(mock_packages, mock_archive, mock_fetch,
-                                        config, install_mockery):
+def test_install_output_on_python_error(
+        mock_packages, mock_archive, mock_fetch, config, install_mockery):
     out = install('failing-build', fail_on_error=False)
     assert isinstance(install.error, spack.build_environment.ChildError)
     assert install.error.name == 'InstallError'

lib/spack/spack/test/concretize.py

@@ -24,8 +24,9 @@
 ##############################################################################
 import pytest
 import llnl.util.lang
-import spack
+
 import spack.architecture
+import spack.repo
 
 from spack.concretize import find_spec
 from spack.spec import Spec, CompilerSpec
@@ -161,7 +162,7 @@ def test_concretize_with_provides_when(self):
         """Make sure insufficient versions of MPI are not in providers list when
         we ask for some advanced version.
         """
-        repo = spack.repo
+        repo = spack.repo.path()
         assert not any(
             s.satisfies('mpich2@:1.0') for s in repo.providers_for('mpi@2.1')
         )
@@ -181,7 +182,7 @@ def test_concretize_with_provides_when(self):
     def test_provides_handles_multiple_providers_of_same_vesrion(self):
         """
         """
-        providers = spack.repo.providers_for('mpi@3.0')
+        providers = spack.repo.path().providers_for('mpi@3.0')
 
         # Note that providers are repo-specific, so we don't misinterpret
         # providers, but vdeps are not namespace-specific, so we can
@@ -216,8 +217,6 @@ def test_architecture_deep_inheritance(self):
         information from the root even when partial architecture information
         is provided by an intermediate dependency.
         """
-        saved_repo = spack.repo
-
         default_dep = ('link', 'build')
 
         bazpkg = MockPackage('bazpkg', [], [])
@@ -225,9 +224,7 @@ def test_architecture_deep_inheritance(self):
         foopkg = MockPackage('foopkg', [barpkg], [default_dep])
         mock_repo = MockPackageMultiRepo([foopkg, barpkg, bazpkg])
 
-        spack.repo = mock_repo
-
-        try:
+        with spack.repo.swap(mock_repo):
             spec = Spec('foopkg %clang@3.3 os=CNL target=footar' +
                         ' ^barpkg os=SuSE11 ^bazpkg os=be')
             spec.concretize()
@@ -235,9 +232,6 @@ def test_architecture_deep_inheritance(self):
             for s in spec.traverse(root=False):
                 assert s.architecture.target == spec.architecture.target
 
-        finally:
-            spack.repo = saved_repo
-
     def test_compiler_flags_from_user_are_grouped(self):
         spec = Spec('a%gcc cflags="-O -foo-flag foo-val" platform=test')
         spec.concretize()

lib/spack/spack/test/concretize_preferences.py

@@ -25,6 +25,7 @@
 import pytest
 
 import spack.package_prefs
+import spack.repo
 import spack.util.spack_yaml as syaml
 from spack.config import ConfigScope
 from spack.spec import Spec
@@ -41,7 +42,7 @@ def concretize_scope(config, tmpdir):
 
     config.pop_scope()
     spack.package_prefs.PackagePrefs.clear_caches()
-    spack.repo._provider_index = None
+    spack.repo.path()._provider_index = None
 
 
 def concretize(abstract_spec):

lib/spack/spack/test/conftest.py

@@ -33,7 +33,6 @@
 
 from llnl.util.filesystem import remove_linked_tree
 
-import spack
 import spack.architecture
 import spack.config
 import spack.caches
@@ -41,7 +40,7 @@
 import spack.directory_layout
 import spack.paths
 import spack.platforms.test
-import spack.repository
+import spack.repo
 import spack.stage
 import spack.util.ordereddict
 import spack.util.executable
@@ -173,25 +172,23 @@ def __str__(self):
 @pytest.fixture(scope='session')
 def repo_path():
     """Session scoped RepoPath object pointing to the mock repository"""
-    return spack.repository.RepoPath(spack.paths.mock_packages_path)
+    return spack.repo.RepoPath(spack.paths.mock_packages_path)
 
 
 @pytest.fixture(scope='module')
 def mock_packages(repo_path):
     """Use the 'builtin.mock' repository instead of 'builtin'"""
     mock_repo = copy.deepcopy(repo_path)
-    spack.repo.swap(mock_repo)
-    yield
-    spack.repo.swap(mock_repo)
+    with spack.repo.swap(mock_repo):
+        yield
 
 
 @pytest.fixture(scope='function')
 def mutable_mock_packages(mock_packages, repo_path):
     """Function-scoped mock packages, for tests that need to modify them."""
     mock_repo = copy.deepcopy(repo_path)
-    spack.repo.swap(mock_repo)
-    yield
-    spack.repo.swap(mock_repo)
+    with spack.repo.swap(mock_repo):
+        yield
 
 
 @pytest.fixture(scope='session')
@@ -221,6 +218,7 @@ def configuration_dir(tmpdir_factory, linux_os):
     compilers_yaml = test_path.join('data', 'compilers.yaml')
     packages_yaml = test_path.join('data', 'packages.yaml')
     config_yaml = test_path.join('data', 'config.yaml')
+    repos_yaml = test_path.join('data', 'repos.yaml')
 
     # Create temporary 'site' and 'user' folders
     tmpdir.ensure('site', dir=True)
@@ -229,6 +227,7 @@ def configuration_dir(tmpdir_factory, linux_os):
     # Copy the configurations that don't need further work
     packages_yaml.copy(tmpdir.join('site', 'packages.yaml'))
     config_yaml.copy(tmpdir.join('site', 'config.yaml'))
+    repos_yaml.copy(tmpdir.join('site', 'repos.yaml'))
 
     # Write the one that needs modifications
     content = ''.join(compilers_yaml.read()).format(linux_os)
@@ -245,8 +244,6 @@ def config(configuration_dir):
 
     real_configuration = spack.config._configuration
 
-    print real_configuration
-
     scopes = [
         spack.config.ConfigScope(name, str(configuration_dir.join(name)))
         for name in ['site', 'system', 'user']]

lib/spack/spack/test/data/repos.yaml

@@ -0,0 +1,2 @@
+repos:
+  - $spack/var/spack/repos/builtin

lib/spack/spack/test/database.py

@@ -33,7 +33,7 @@
 
 from llnl.util.tty.colify import colify
 
-import spack
+import spack.repo
 import spack.store
 from spack.test.conftest import MockPackageMultiRepo
 from spack.util.executable import Executable
@@ -432,17 +432,12 @@ def fail_while_writing():
 def test_115_reindex_with_packages_not_in_repo(database, refresh_db_on_exit):
     install_db = database.mock.db
 
-    saved_repo = spack.repo
     # Dont add any package definitions to this repository, the idea is that
     # packages should not have to be defined in the repository once they
     # are installed
-    mock_repo = MockPackageMultiRepo([])
-    try:
-        spack.repo = mock_repo
+    with spack.repo.swap(MockPackageMultiRepo([])):
         spack.store.db.reindex(spack.store.layout)
         _check_db_sanity(install_db)
-    finally:
-        spack.repo = saved_repo
 
 
 def test_external_entries_in_db(database):

lib/spack/spack/test/directory_layout.py

@@ -30,11 +30,10 @@
 
 from llnl.util.filesystem import join_path
 
-import spack
 import spack.paths
+import spack.repo
 from spack.directory_layout import YamlDirectoryLayout
 from spack.directory_layout import InvalidDirectoryLayoutParametersError
-from spack.repository import RepoPath
 from spack.spec import Spec
 
 # number of packages to test (to reduce test time)
@@ -105,7 +104,7 @@ def test_read_and_write_spec(
     layout.
     """
     layout, tmpdir = layout_and_dir
-    packages = list(spack.repo.all_packages())[:max_packages]
+    packages = list(spack.repo.path().all_packages())[:max_packages]
 
     for pkg in packages:
         if pkg.name.startswith('external'):
@@ -187,7 +186,7 @@ def test_handle_unknown_package(
     or query them again if the package goes away.
     """
     layout, _ = layout_and_dir
-    mock_db = RepoPath(spack.paths.mock_packages_path)
+    mock_db = spack.repo.RepoPath(spack.paths.mock_packages_path)
 
     not_in_mock = set.difference(
         set(spack.repo.all_package_names()),
@@ -209,28 +208,25 @@ def test_handle_unknown_package(
         layout.create_install_directory(spec)
         installed_specs[spec] = layout.path_for_spec(spec)
 
-    spack.repo.swap(mock_db)
+    with spack.repo.swap(mock_db):
+        # Now check that even without the package files, we know
+        # enough to read a spec from the spec file.
+        for spec, path in installed_specs.items():
+            spec_from_file = layout.read_spec(
+                join_path(path, '.spack', 'spec.yaml'))
 
-    # Now check that even without the package files, we know
-    # enough to read a spec from the spec file.
-    for spec, path in installed_specs.items():
-        spec_from_file = layout.read_spec(
-            join_path(path, '.spack', 'spec.yaml')
-        )
-        # To satisfy these conditions, directory layouts need to
-        # read in concrete specs from their install dirs somehow.
-        assert path == layout.path_for_spec(spec_from_file)
-        assert spec == spec_from_file
-        assert spec.eq_dag(spec_from_file)
-        assert spec.dag_hash() == spec_from_file.dag_hash()
-
-    spack.repo.swap(mock_db)
+            # To satisfy these conditions, directory layouts need to
+            # read in concrete specs from their install dirs somehow.
+            assert path == layout.path_for_spec(spec_from_file)
+            assert spec == spec_from_file
+            assert spec.eq_dag(spec_from_file)
+            assert spec.dag_hash() == spec_from_file.dag_hash()
 
 
 def test_find(layout_and_dir, config, mock_packages):
     """Test that finding specs within an install layout works."""
     layout, _ = layout_and_dir
-    packages = list(spack.repo.all_packages())[:max_packages]
+    packages = list(spack.repo.path().all_packages())[:max_packages]
 
     # Create install prefixes for all packages in the list
     installed_specs = {}

lib/spack/spack/test/flag_handlers.py

@@ -26,6 +26,7 @@
 import os
 
 import spack.spec
+import spack.repo
 import spack.build_environment
 
 

lib/spack/spack/test/git_fetch.py

@@ -28,7 +28,7 @@
 
 from llnl.util.filesystem import working_dir, join_path, touch
 
-import spack
+import spack.repo
 import spack.config
 from spack.spec import Spec
 from spack.version import ver

lib/spack/spack/test/hg_fetch.py

@@ -28,7 +28,7 @@
 
 from llnl.util.filesystem import working_dir, join_path, touch
 
-import spack
+import spack.repo
 import spack.config
 from spack.spec import Spec
 from spack.version import ver

lib/spack/spack/test/install.py

@@ -25,7 +25,7 @@
 import os
 import pytest
 
-import spack
+import spack.repo
 import spack.store
 from spack.spec import Spec
 

lib/spack/spack/test/mirror.py

@@ -28,7 +28,7 @@
 
 from llnl.util.filesystem import join_path
 
-import spack
+import spack.repo
 import spack.mirror
 import spack.util.executable
 from spack.spec import Spec

lib/spack/spack/test/multimethod.py

@@ -23,8 +23,9 @@
 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ##############################################################################
 """Test for multi_method dispatch."""
-import spack
 import pytest
+
+import spack.repo
 from spack.multimethod import NoSuchMethodError
 
 

lib/spack/spack/test/package_sanity.py

@@ -27,9 +27,9 @@
 
 import pytest
 
-import spack
+import spack.repo
 from spack.paths import mock_packages_path
-from spack.repository import RepoPath
+from spack.repo import RepoPath
 
 
 def check_db():
@@ -47,9 +47,8 @@ def test_get_all_packages():
 def test_get_all_mock_packages():
     """Get the mock packages once each too."""
     db = RepoPath(mock_packages_path)
-    spack.repo.swap(db)
-    check_db()
-    spack.repo.swap(db)
+    with spack.repo.swap(db):
+        check_db()
 
 
 def test_all_versions_are_lowercase():
@@ -66,7 +65,7 @@ def test_all_virtual_packages_have_default_providers():
     """All virtual packages must have a default provider explicitly set."""
     defaults = spack.config.get('packages', scope='defaults')
     default_providers = defaults['all']['providers']
-    providers = spack.repo.provider_index.providers
+    providers = spack.repo.path().provider_index.providers
 
     for provider in providers:
         assert provider in default_providers

lib/spack/spack/test/packages.py

@@ -26,9 +26,8 @@
 
 from llnl.util.filesystem import join_path
 
-import spack
+import spack.repo
 from spack.paths import mock_packages_path
-from spack.repository import Repo
 from spack.util.naming import mod_to_class
 from spack.spec import Spec
 from spack.util.package_hash import package_content
@@ -44,7 +43,7 @@ def test_package_name(self):
         assert pkg.name == 'mpich'
 
     def test_package_filename(self):
-        repo = Repo(mock_packages_path)
+        repo = spack.repo.Repo(mock_packages_path)
         filename = repo.filename_for_package_name('mpich')
         assert filename == join_path(
             mock_packages_path,
@@ -54,7 +53,7 @@ def test_package_filename(self):
         )
 
     def test_nonexisting_package_filename(self):
-        repo = Repo(mock_packages_path)
+        repo = spack.repo.Repo(mock_packages_path)
         filename = repo.filename_for_package_name('some-nonexisting-package')
         assert filename == join_path(
             mock_packages_path,

lib/spack/spack/test/packaging.py

@@ -34,7 +34,7 @@
 
 from llnl.util.filesystem import mkdirp
 
-import spack
+import spack.repo
 import spack.store
 import spack.binary_distribution as bindist
 import spack.cmd.buildcache as buildcache

lib/spack/spack/test/provider_index.py

@@ -39,7 +39,7 @@
 """
 from six import StringIO
 
-import spack
+import spack.repo
 from spack.provider_index import ProviderIndex
 from spack.spec import Spec
 

lib/spack/spack/test/repo.py

@@ -24,7 +24,7 @@
 ##############################################################################
 import pytest
 
-import spack.repository
+import spack.repo
 import spack.paths
 
 
@@ -33,7 +33,7 @@
 # given RepoPath
 @pytest.fixture()
 def repo_for_test():
-    return spack.repository.RepoPath(spack.paths.mock_packages_path)
+    return spack.repo.RepoPath(spack.paths.mock_packages_path)
 
 
 @pytest.fixture()
@@ -47,7 +47,7 @@ def extra_repo(tmpdir_factory):
 repo:
   namespace: extra_test_repo
 """)
-    return spack.repository.Repo(str(repo_dir))
+    return spack.repo.Repo(str(repo_dir))
 
 
 def test_repo_getpkg(repo_for_test):
@@ -68,10 +68,10 @@ def test_repo_multi_getpkgclass(repo_for_test, extra_repo):
 
 
 def test_repo_pkg_with_unknown_namespace(repo_for_test):
-    with pytest.raises(spack.repository.UnknownNamespaceError):
+    with pytest.raises(spack.repo.UnknownNamespaceError):
         repo_for_test.get('unknown.a')
 
 
 def test_repo_unknown_pkg(repo_for_test):
-    with pytest.raises(spack.repository.UnknownPackageError):
+    with pytest.raises(spack.repo.UnknownPackageError):
         repo_for_test.get('builtin.mock.nonexistentpackage')

lib/spack/spack/test/spec_dag.py

@@ -86,8 +86,6 @@ def test_test_deptype():
 w->y deptypes are (link, build), w->x and y->z deptypes are (test)
 
 """
-    saved_repo = spack.repo
-
     default = ('build', 'link')
     test_only = ('test',)
 
@@ -97,15 +95,12 @@ def test_test_deptype():
     w = MockPackage('w', [x, y], [test_only, default])
 
     mock_repo = MockPackageMultiRepo([w, x, y, z])
-    try:
-        spack.repo = mock_repo
+    with spack.repo.swap(mock_repo):
         spec = Spec('w')
         spec.concretize(tests=(w.name,))
 
         assert ('x' in spec)
         assert ('z' not in spec)
-    finally:
-        spack.repo = saved_repo
 
 
 @pytest.mark.usefixtures('mutable_mock_packages')

lib/spack/spack/test/svn_fetch.py

@@ -28,7 +28,7 @@
 
 from llnl.util.filesystem import join_path, touch, working_dir
 
-import spack
+import spack.repo
 import spack.config
 from spack.spec import Spec
 from spack.version import ver

lib/spack/spack/test/url_fetch.py

@@ -27,7 +27,7 @@
 
 from llnl.util.filesystem import working_dir, is_exe
 
-import spack
+import spack.repo
 import spack.config
 from spack.fetch_strategy import from_list_url, URLFetchStrategy
 from spack.spec import Spec

lib/spack/spack/util/package_hash.py

@@ -22,7 +22,7 @@
 # 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
+import spack.repo
 from spack import directives
 from spack.error import SpackError
 from spack.spec import Spec
@@ -131,7 +131,7 @@ def package_hash(spec, content=None):
 def package_ast(spec):
     spec = Spec(spec)
 
-    filename = spack.repo.filename_for_package_name(spec.name)
+    filename = spack.repo.path().filename_for_package_name(spec.name)
     with open(filename) as f:
         text = f.read()
         root = ast.parse(text)