Fix bugs with sparse spec printing.

- Make namespace, arch, and dependnecies show up in spec yaml
  only if they're set.

- Lost some of this functionality with deptypes

lib/spack/spack/architecture.py

@@ -383,6 +383,13 @@ def __str__(self):
     def __contains__(self, string):
         return string in str(self)
 
+    # TODO: make this unnecessary: don't include an empty arch on *every* spec.
+    def __nonzero__(self):
+        return (self.platform is not None or
+                self.platform_os is not None or
+                self.target is not None)
+    __bool__ = __nonzero__
+
     def _cmp_key(self):
         if isinstance(self.platform, Platform):
             platform = self.platform.name

lib/spack/spack/spec.py

@@ -915,10 +915,7 @@ def to_node_dict(self):
         if params:
             d['parameters'] = params
 
-        if self.architecture is not None:
+        if self.dependencies():
-            d['arch'] = self.architecture
-
-        if self.dependencies:
             deps = self.dependencies_dict(deptype=('link', 'run'))
             d['dependencies'] = dict(
                 (name, {
@@ -926,17 +923,13 @@ def to_node_dict(self):
                     'type': [str(s) for s in dspec.deptypes]})
                 for name, dspec in deps.items())
 
-        # Older concrete specs do not have a namespace.  Omit for
+        if self.namespace:
-        # consistent hashing.
-        if not self.concrete or self.namespace:
             d['namespace'] = self.namespace
 
         if self.architecture:
             # TODO: Fix the target.to_dict to account for the tuple
             # Want it to be a dict of dicts
             d['arch'] = self.architecture.to_dict()
-        else:
-            d['arch'] = None
 
         if self.compiler:
             d.update(self.compiler.to_dict())
@@ -967,7 +960,8 @@ def from_node_dict(node):
         if 'version' in node or 'versions' in node:
             spec.versions = VersionList.from_dict(node)
 
-        spec.architecture = spack.architecture.arch_from_dict(node['arch'])
+        if 'arch' in node:
+            spec.architecture = spack.architecture.arch_from_dict(node['arch'])
 
         if 'compiler' in node:
             spec.compiler = CompilerSpec.from_dict(node)

lib/spack/spack/test/architecture.py

@@ -86,6 +86,29 @@ def test_platform(self):
 
         self.assertEqual(str(output_platform_class), str(my_platform_class))
 
+    def test_boolness(self):
+        # Make sure architecture reports that it's False when nothing's set.
+        arch = spack.architecture.Arch()
+        self.assertFalse(arch)
+
+        # Dummy architecture parts
+        plat = spack.architecture.platform()
+        plat_os = plat.operating_system('default_os')
+        plat_target = plat.target('default_target')
+
+        # Make sure architecture reports that it's True when anything is set.
+        arch = spack.architecture.Arch()
+        arch.platform = plat
+        self.assertTrue(arch)
+
+        arch = spack.architecture.Arch()
+        arch.platform_os = plat_os
+        self.assertTrue(arch)
+
+        arch = spack.architecture.Arch()
+        arch.target = plat_target
+        self.assertTrue(arch)
+
     def test_user_front_end_input(self):
         """Test when user inputs just frontend that both the frontend target
             and frontend operating system match