config: create internal config scope for commands to use.

5 files changed, 87 insertions, 13 deletions

diff --git a/lib/spack/spack/compilers/__init__.py b/lib/spack/spack/compilers/__init__.py
index ed6d4c8db2..eb637259b5 100644
--- a/lib/spack/spack/compilers/__init__.py
+++ b/lib/spack/spack/compilers/__init__.py
@@ -117,10 +117,11 @@ def get_compiler_config(scope=None, init_config=True):
 def compiler_config_files():
     config_files = list()
     config = spack.config.get_configuration()
-    for scope in config.scopes:
-        compiler_config = config.get_config('compilers', scope=scope)
+    for scope in config.file_scopes:
+        name = scope.name
+        compiler_config = config.get_config('compilers', scope=name)
         if compiler_config:
-            config_files.append(config.get_config_filename(scope, 'compilers'))
+            config_files.append(config.get_config_filename(name, 'compilers'))
     return config_files
 
 
diff --git a/lib/spack/spack/config.py b/lib/spack/spack/config.py
index 1a32a2ddd4..d622f0416d 100644
--- a/lib/spack/spack/config.py
+++ b/lib/spack/spack/config.py
@@ -109,6 +109,10 @@ configuration_paths = (
 scopes_metavar = '{defaults,system,site,user}[/PLATFORM]'
 
 
+#: config scopes only used by Spack internally
+internal_scopes = ['commands']
+
+
 def _extend_with_default(validator_class):
     """Add support for the 'default' attr for properties and patternProperties.
 
@@ -199,6 +203,37 @@ class ConfigScope(object):
         return '<ConfigScope: %s: %s>' % (self.name, self.path)
 
 
+class InternalConfigScope(ConfigScope):
+    """An internal configuration scope that is not persisted to a file.
+
+    This is for spack internal use so that command-line options and
+    config file settings are accessed the same way, and Spack can easily
+    override settings from files.
+    """
+    def __init__(self, name):
+        self.name = name
+        self.sections = syaml.syaml_dict()
+
+    def get_section_filename(self, section):
+        raise NotImplementedError(
+            "Cannot get filename for InternalConfigScope.")
+
+    def get_section(self, section):
+        """Just reads from an internal dictionary."""
+        if section not in self.sections:
+            self.sections[section] = None
+        return self.sections[section]
+
+    def write_section(self, section):
+        """This only validates, as the data is already in memory."""
+        data = self.get_section(section)
+        if data is not None:
+            _validate_section(data, section_schemas[section])
+
+    def __repr__(self):
+        return '<InternalConfigScope: %s>' % self.name
+
+
 class Configuration(object):
     """A full Spack configuration, from a hierarchy of config files.
 
@@ -226,10 +261,15 @@ class Configuration(object):
         name, scope = self.scopes.popitem(last=True)
         return scope
 
+    @property
+    def file_scopes(self):
+        """List of scopes with an associated file (non-internal scopes)."""
+        return [s for s in self.scopes.values()
+                if not isinstance(s, InternalConfigScope)]
+
     def highest_precedence_scope(self):
-        """Get the scope with highest precedence (prefs will override others).
-        """
-        return list(self.scopes.values())[-1]
+        """Non-internal scope with highest precedence."""
+        return next(reversed(self.file_scopes), None)
 
     def _validate_scope(self, scope):
         """Ensure that scope is valid in this configuration.
@@ -371,17 +411,19 @@ def get_configuration():
         # configuration directory.
         platform = spack.architecture.platform().name
 
-        scopes = []
+        _configuration = Configuration()
         for name, path in configuration_paths:
             # add the regular scope
-            scopes.append(ConfigScope(name, path))
+            _configuration.push_scope(ConfigScope(name, path))
 
             # add platform-specific scope
             plat_name = '%s/%s' % (name, platform)
             plat_path = os.path.join(path, platform)
-            scopes.append(ConfigScope(plat_name, plat_path))
+            _configuration.push_scope(ConfigScope(plat_name, plat_path))
 
-        _configuration = Configuration(*scopes)
+        # we make a special scope for spack commands so that they can
+        # override configuration options.
+        _configuration.push_scope(InternalConfigScope('commands'))
 
     return _configuration
 
diff --git a/lib/spack/spack/fetch_strategy.py b/lib/spack/spack/fetch_strategy.py
index 04e42a9f0c..779a4315fe 100644
--- a/lib/spack/spack/fetch_strategy.py
+++ b/lib/spack/spack/fetch_strategy.py
@@ -52,6 +52,7 @@ import llnl.util.tty as tty
 from llnl.util.filesystem import working_dir, mkdirp, join_path
 
 import spack
+import spack.config
 import spack.error
 import spack.util.crypto as crypto
 import spack.util.pattern as pattern
diff --git a/lib/spack/spack/hooks/yaml_version_check.py b/lib/spack/spack/hooks/yaml_version_check.py
index ec695319d1..a2bccf1fb1 100644
--- a/lib/spack/spack/hooks/yaml_version_check.py
+++ b/lib/spack/spack/hooks/yaml_version_check.py
@@ -38,7 +38,7 @@ def pre_run():
 def check_compiler_yaml_version():
     config = spack.config.get_configuration()
 
-    for scope in config:
+    for scope in config.file_scopes:
         file_name = os.path.join(scope.path, 'compilers.yaml')
         data = None
         if os.path.isfile(file_name):
diff --git a/lib/spack/spack/test/config.py b/lib/spack/spack/test/config.py
index 17e749d6a2..41b02d493e 100644
--- a/lib/spack/spack/test/config.py
+++ b/lib/spack/spack/test/config.py
@@ -64,9 +64,10 @@ def config(tmpdir):
     real_configuration = spack.config._configuration
     scopes = [spack.config.ConfigScope(name, str(tmpdir.join(name)))
               for name in ['low', 'high']]
-    spack.config._configuration = spack.config.Configuration(*scopes)
+    config = spack.config.Configuration(*scopes)
+    spack.config._configuration = config
 
-    yield
+    yield config
 
     spack.config._configuration = real_configuration
 
@@ -420,6 +421,35 @@ def test_read_config_override_list(config, write_config_file):
     }
 
 
+def test_internal_config_update(config, write_config_file):
+    write_config_file('config', config_low, 'low')
+
+    before = config.get_config('config')
+    assert before['install_tree'] == 'install_tree_path'
+
+    # add an internal configuration scope
+    scope = spack.config.InternalConfigScope('commands')
+    assert 'InternalConfigScope' in repr(scope)
+
+    config.push_scope(scope)
+
+    command_config = config.get_config('config', scope='commands')
+    command_config['install_tree'] = 'foo/bar'
+
+    config.update_config('config', command_config, scope='commands')
+
+    after = config.get_config('config')
+    assert after['install_tree'] == 'foo/bar'
+
+
+def test_internal_config_filename(config, write_config_file):
+    write_config_file('config', config_low, 'low')
+    config.push_scope(spack.config.InternalConfigScope('commands'))
+
+    with pytest.raises(NotImplementedError):
+        config.get_config_filename('commands', 'config')
+
+
 def test_keys_are_ordered():
 
     expected_order = (