repos: introduce a factory to abstract away from Repo implementation

The user just calls that factory and gets something that is a Repo, in
fact just a GitRepo for now.

Signed-off-by: Henning Schild <henning.schild@siemens.com>

kas/config.py

@@ -199,16 +199,12 @@ class Config:
                                  name)
 
                 url = path
-                rep = Repo(url=url,
-                           path=path,
-                           layers=layers)
+                rep = Repo.factory(url=url, path=path, layers=layers)
                 rep.disable_operations()
             else:
                 path = path or os.path.join(self.kas_work_dir, name)
-                rep = Repo(url=url,
-                           path=path,
-                           refspec=refspec,
-                           layers=layers)
+                rep = Repo.factory(url=url, path=path, refspec=refspec,
+                                   layers=layers)
             repo_dict[repo] = rep
         return repo_dict
 

kas/repos.py

@@ -38,7 +38,7 @@ class Repo:
         Represents a repository in the kas configuration.
     """
 
-    def __init__(self, url, path, refspec=None, layers=None):
+    def __init__(self, url, path, refspec, layers):
         self.url = url
         self.path = path
         self.refspec = refspec
@@ -73,6 +73,36 @@ class Repo:
         return '%s:%s %s %s' % (self.url, self.refspec,
                                 self.path, self._layers)
 
+    @staticmethod
+    def factory(url, path, refspec=None, layers=None):
+        """
+            Return an instance Repo depending on params.
+        """
+        return GitRepo(url, path, refspec, layers)
+
+    @staticmethod
+    def get_root_path(path, environ):
+        """
+            Check if path is a version control repo and return its root path.
+        """
+        (ret, output) = run_cmd(['git',
+                                 'rev-parse',
+                                 '--show-toplevel'],
+                                cwd=path,
+                                env=environ,
+                                fail=False,
+                                liveupdate=False)
+        if ret == 0:
+            return output.strip()
+
+        return path
+
+
+class GitRepo(Repo):
+    """
+        Provides the git implementations for a Repo.
+    """
+
     @asyncio.coroutine
     def fetch_async(self, config):
         """
@@ -155,20 +185,3 @@ class Repo:
         run_cmd(['git', 'checkout', '-q',
                  '{refspec}'.format(refspec=self.refspec)],
                 cwd=self.path)
-
-    @staticmethod
-    def get_root_path(path, environ):
-        """
-            Check if path is a version control repo and return its root path.
-        """
-        (ret, output) = run_cmd(['git',
-                                 'rev-parse',
-                                 '--show-toplevel'],
-                                cwd=path,
-                                env=environ,
-                                fail=False,
-                                liveupdate=False)
-        if ret == 0:
-            return output.strip()
-
-        return path