Move concretization into its own class.

Allows easy overriding of a single policy.

lib/spack/spack/concretize.py

@@ -15,7 +15,13 @@
 from spack.spec import *
 
 
-def concretize_version(spec):
+class DefaultConcretizer(object):
+    """This class doesn't have any state, it just provides some methods for
+       concretization.  You can subclass it to override just some of the
+       default concretization strategies, or you can override all of them.
+    """
+
+    def concretize_version(self, spec):
         """If the spec is already concrete, return.  Otherwise take
            the most recent available version, and default to the package's
            version if there are no avaialble versions.
@@ -34,7 +40,7 @@ def concretize_version(spec):
             spec.versions = ver([pkg.version])
 
 
-def concretize_architecture(spec):
+    def concretize_architecture(self, spec):
         """If the spec already had an architecture, return.  Otherwise if
            the root of the DAG has an architecture, then use that.
            Otherwise take the system's default architecture.
@@ -57,7 +63,7 @@ def concretize_architecture(spec):
             spec.architecture = spack.arch.sys_type()
 
 
-def concretize_compiler(spec):
+    def concretize_compiler(self, spec):
         """Currently just sets the compiler to gcc or throws an exception
            if the compiler is set to something else.
 

lib/spack/spack/globals.py

@@ -5,6 +5,7 @@
 from spack.util.filesystem import *
 from spack.util.executable import *
 from spack.directory_layout import DefaultDirectoryLayout
+from spack.concretize import DefaultConcretizer
 
 # This lives in $prefix/lib/spac/spack/__file__
 prefix = ancestor(__file__, 4)
@@ -31,6 +32,13 @@
 #
 install_layout = DefaultDirectoryLayout(install_path)
 
+#
+# This controls how things are concretized in spack.
+# Replace it with a subclass if you want different
+# policies.
+#
+concretizer = DefaultConcretizer()
+
 # Version information
 spack_version = Version("0.5")
 

lib/spack/spack/relations.py

@@ -81,4 +81,4 @@ def provides(*args):
     # Get the enclosing package's scope and add deps to it.
     provided = _caller_locals().setdefault("provided", [])
     for name in args:
-        provides.append(name)
+        provided.append(name)

lib/spack/spack/spec.py

@@ -67,7 +67,6 @@
 import tty
 import spack.parse
 import spack.error
-import spack.concretize
 import spack.compilers
 import spack.compilers.gcc
 import spack.packages as packages
@@ -330,6 +329,8 @@ def virtual(self):
         """Right now, a spec is virtual if no package exists with its name.
            TODO: revisit this -- might need to use a separate namespace and
                  be more explicit about this.
+                 Possible idea: just use conventin and make virtual deps all
+                 caps, e.g., MPI vs mpi.
         """
         return not packages.exists(self.name)
 
@@ -400,9 +401,9 @@ def _concretize_helper(self, presets):
         if self.name in presets:
             self.constrain(presets[self.name])
         else:
-            spack.concretize.concretize_architecture(self)
-            spack.concretize.concretize_compiler(self)
-            spack.concretize.concretize_version(self)
+            spack.concretizer.concretize_architecture(self)
+            spack.concretizer.concretize_compiler(self)
+            spack.concretizer.concretize_version(self)
             presets[self.name] = self
 
 

lib/spack/spack/test/mock_packages/mpich.py

@@ -10,6 +10,8 @@ class Mpich(Package):
 
     versions = '1.0.3, 1.3.2p1, 1.4.1p1, 3.0.4, 3.1b1'
 
+    provides('mpi')
+
     def install(self, prefix):
         configure("--prefix=%s" % prefix)
         make()