Move concretization into its own class.

Allows easy overriding of a single policy.

5 files changed, 73 insertions, 56 deletions

diff --git a/lib/spack/spack/concretize.py b/lib/spack/spack/concretize.py
index 6acae39039..2d33a544e0 100644
--- a/lib/spack/spack/concretize.py
+++ b/lib/spack/spack/concretize.py
@@ -15,66 +15,72 @@ from spack.version import *
 from spack.spec import *
 
 
-def concretize_version(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.
+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.
     """
-    # return if already concrete.
-    if spec.versions.concrete:
-        return
 
-    pkg = spec.package
+    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.
+        """
+        # return if already concrete.
+        if spec.versions.concrete:
+            return
 
-    # If there are known avaialble versions, return the most recent
-    available_versions = pkg.available_versions
-    if available_versions:
-        spec.versions = ver([available_versions[-1]])
-    else:
-        spec.versions = ver([pkg.version])
+        pkg = spec.package
 
+        # If there are known avaialble versions, return the most recent
+        available_versions = pkg.available_versions
+        if available_versions:
+            spec.versions = ver([available_versions[-1]])
+        else:
+            spec.versions = ver([pkg.version])
 
-def concretize_architecture(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.
 
-       Intuition: Architectures won't be set a lot, and generally you
-       want the host system's architecture.  When architectures are
-       mised in a spec, it is likely because the tool requries a
-       cross-compiled component, e.g. for tools that run on BlueGene
-       or Cray machines.  These constraints will likely come directly
-       from packages, so require the user to be explicit if they want
-       to mess with the architecture, and revert to the default when
-       they're not explicit.
-    """
-    if spec.architecture is not None:
-        return
+    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.
 
-    if spec.root.architecture:
-        spec.architecture = spec.root.architecture
-    else:
-        spec.architecture = spack.arch.sys_type()
+           Intuition: Architectures won't be set a lot, and generally you
+           want the host system's architecture.  When architectures are
+           mised in a spec, it is likely because the tool requries a
+           cross-compiled component, e.g. for tools that run on BlueGene
+           or Cray machines.  These constraints will likely come directly
+           from packages, so require the user to be explicit if they want
+           to mess with the architecture, and revert to the default when
+           they're not explicit.
+        """
+        if spec.architecture is not None:
+            return
 
+        if spec.root.architecture:
+            spec.architecture = spec.root.architecture
+        else:
+            spec.architecture = spack.arch.sys_type()
 
-def concretize_compiler(spec):
-    """Currently just sets the compiler to gcc or throws an exception
-       if the compiler is set to something else.
 
-       TODO: implement below description.
+    def concretize_compiler(self, spec):
+        """Currently just sets the compiler to gcc or throws an exception
+           if the compiler is set to something else.
 
-       If the spec already has a compiler, we're done.  If not, then
-       take the compiler used for the nearest ancestor with a concrete
-       compiler, or use the system default if there is no ancestor
-       with a compiler.
+           TODO: implement below description.
 
-       Intuition: Use the system default if no package that depends on
-       this one has a strict compiler requirement.  Otherwise, try to
-       build with the compiler that will be used by libraries that
-       link to this one, to maximize compatibility.
-    """
-    if spec.compiler and spec.compiler.concrete:
-        if spec.compiler != spack.compilers.default_compiler():
-            raise spack.spec.UnknownCompilerError(str(spec.compiler))
-    else:
-        spec.compiler = spack.compilers.default_compiler()
+           If the spec already has a compiler, we're done.  If not, then
+           take the compiler used for the nearest ancestor with a concrete
+           compiler, or use the system default if there is no ancestor
+           with a compiler.
+
+           Intuition: Use the system default if no package that depends on
+           this one has a strict compiler requirement.  Otherwise, try to
+           build with the compiler that will be used by libraries that
+           link to this one, to maximize compatibility.
+        """
+        if spec.compiler and spec.compiler.concrete:
+            if spec.compiler != spack.compilers.default_compiler():
+                raise spack.spec.UnknownCompilerError(str(spec.compiler))
+        else:
+            spec.compiler = spack.compilers.default_compiler()
diff --git a/lib/spack/spack/globals.py b/lib/spack/spack/globals.py
index 3b2359e21d..7b746a0734 100644
--- a/lib/spack/spack/globals.py
+++ b/lib/spack/spack/globals.py
@@ -5,6 +5,7 @@ from spack.version import Version
 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_path   = new_path(prefix, "opt")
 #
 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")
 
diff --git a/lib/spack/spack/relations.py b/lib/spack/spack/relations.py
index f936f6e364..0d1983257b 100644
--- a/lib/spack/spack/relations.py
+++ b/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)
diff --git a/lib/spack/spack/spec.py b/lib/spack/spack/spec.py
index 73542b9179..d14957c23b 100644
--- a/lib/spack/spack/spec.py
+++ b/lib/spack/spack/spec.py
@@ -67,7 +67,6 @@ from StringIO import StringIO
 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 @@ class Spec(object):
         """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 @@ class Spec(object):
         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
 
 
diff --git a/lib/spack/spack/test/mock_packages/mpich.py b/lib/spack/spack/test/mock_packages/mpich.py
index 85c4c2d939..2972c34df0 100644
--- a/lib/spack/spack/test/mock_packages/mpich.py
+++ b/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()