resource : fetch strategy constructed from kwargs instead or hardcoded URLFetchStrategy

lib/spack/spack/directives.py

@@ -62,7 +62,7 @@ class OpenMpi(Package):
 from spack.variant import Variant
 from spack.spec import Spec, parse_anonymous_spec
 from spack.resource import Resource
-from spack.fetch_strategy import URLFetchStrategy
+from spack.fetch_strategy import from_kwargs
 
 #
 # This is a list of all directives, built up as they are defined in
@@ -279,8 +279,7 @@ def resource(pkg, **kwargs):
     destination = kwargs.get('destination', "")
     when_spec = parse_anonymous_spec(when, pkg.name)
     resources = pkg.resources.setdefault(when_spec, [])
-    # FIXME : change URLFetchStrategy with a factory that selects based on kwargs
-    fetcher = URLFetchStrategy(**kwargs)
+    fetcher = from_kwargs(**kwargs)
     # FIXME : should we infer the name somehow if not passed ?
     name = kwargs.get('name')
     resources.append(Resource(name, fetcher, destination))

lib/spack/spack/fetch_strategy.py

@@ -634,6 +634,22 @@ def from_url(url):
     return URLFetchStrategy(url)
 
 
+def from_kwargs(**kwargs):
+    """
+    Construct the appropriate FetchStrategy from the given keyword arguments.
+
+    :param kwargs: dictionary of keyword arguments
+    :return: fetcher or raise a FetchError exception
+    """
+    for fetcher in all_strategies:
+        if fetcher.matches(kwargs):
+            return fetcher(**kwargs)
+    # Raise an error in case we can't instantiate any known strategy
+    message = "Cannot instantiate any FetchStrategy"
+    long_message = message + " from the given arguments : {arguments}".format(srguments=kwargs)
+    raise FetchError(message, long_message)
+
+
 def args_are_for(args, fetcher):
     fetcher.matches(args)