Working plugin architecture

Even if the plugins don't work yet :)

1 files changed, 89 insertions, 29 deletions

diff --git a/nbb/nbb_lib.in b/nbb/nbb_lib.in
index d226fa0..4b5710d 100644
--- a/nbb/nbb_lib.in
+++ b/nbb/nbb_lib.in
@@ -3,65 +3,124 @@ import os
 from subprocess import Popen
 import subprocess
 
-vc_srctree_classes = []
-
-class FooMeta(type):
-    def __init__(self, name, bases, attrs):
-        print ("FooMeta.__init__: name=%s, bases=%s, attrs=%s"
-               % (name, bases, attrs))
-        cls = super(FooMeta, self).__init__(name, bases, attrs)
-        if attrs['platform'] is not None:
-            # register_foo_implementation(cls.platform, cls)
-            vc_srctree_classes.append(cls)
-        return cls
+
+########################################################################
+# Utility functions
+########################################################################
+
+
+def prog_stdout(call_list):
+    p = Popen(call_list, stdout=subprocess.PIPE)
+    stdout, stderr = p.communicate()
+    return stdout.strip()
+
+
+########################################################################
+# VCS Source Tree plugin system
+########################################################################
+
+class NotASourceTree(Exception):
+    pass
+
+class VCSourceTreeMeta(type):
+    vc_srctree_classes = []
+    def __init__(cls, name, bases, attrs):
+        if not hasattr(cls, 'plugins'):
+            # This branch only executes when processing the mount point itself.
+            # So, since this is a new plugin type, not an implementation, this
+            # class shouldn't be registered as a plugin. Instead, it sets up a
+            # list where plugins can be registered later.
+            cls.plugins = []
+        else:
+            # This must be a plugin implementation, which should be registered.
+            # Simply appending it to the list is all that's needed to keep
+            # track of it later.
+            cls.plugins.append(cls)
+
 
 class VCSourceTree(object):
-    __metaclass__ = FooMeta
-    platform = None
-    def __init__(self, srcdir):
-        def check_class(cls):
+    """
+    Mount point for plugins which refer to actions that can be performed.
+
+    Plugins implementing this reference should provide the following
+    interface:
+
+    vcs_name  attribute
+        The text to be displayed, describing the version control system
+    __init__  function
+        Must raise NotASourceTree() if it is not a VCS source tree
+    """
+    __metaclass__ = VCSourceTreeMeta
+
+    def detect(cls, srcdir):
+        def check_class(klass):
             try:
-                return cls(srcdir)
-            except NotASourceTree():
+                return klass(srcdir)
+            except NotASourceTree:
                 return None
-        matches = filter(check_class, vc_srctree_classes)
+        if len(VCSourceTree.plugins) < 1:
+            raise "No VC source tree classes registered"
+        matches = filter(check_class, VCSourceTree.plugins)
         if len(matches) > 1:
             raise ("More than one source tree type detected for '%s'"
                    % (srcdir,))
         elif len(matches) < 1:
             raise "Source tree type for '%s' not detected" % (srcdir,)
         return matches[0]
+    detect = classmethod(detect)
 
-def prog_stdout(call_list):
-    p = Popen(call_list, stdout=subprocess.PIPE)
-    stdout, stderr = p.communicate()
-    return stdout.strip()
 
-class NotASourceTree(Exception):
-    pass
+########################################################################
+# VCS Source Tree plugins
+########################################################################
 
 class GitSourceTree(VCSourceTree):
-    platform = 'git'
+
+    vcs_name = 'git'
+
     def __init__(self, srcdir):
         if "true" != prog_stdout(["git", "rev-parse",
                                   "--is-inside-work-tree"]):
-            raise "Not a git sourcetree"
-        self.top_srcdir = os.path.join(srcdir, FIXME)
+            raise NotASourceTree()
+        self.top_srcdir = os.path.join(srcdir, '.') # FIXME)
+
+    def __str__(self):
+        return "%s(%s)" % (self.__class__.__name__, self.top_srcdir)
+
 
 class BzrSourceTree(VCSourceTree):
-    platform = 'bzr'
+
+    vcs_name = 'bzr'
+
     def __init__(self, srcdir):
         try:
             import bzrlib.workingtree
             wt,b = bzrlib.workingtree.WorkingTree.open_containing(".")
+        except bzrlib.errors.NotBranchError:
+            raise NotASourceTree()
         except ImportError:
             raise NotASourceTree()
         self.wt = wt
+        print "wt:", wt
+        print "b:", b
+        print "wt:", dir(wt)
+        print "b:", dir(b)
+
+    def __str__(self):
+        return "%s(%s)" % (self.__class__.__name__, self.top_srcdir)
+
+
+########################################################################
+# Main program
+########################################################################
 
 class NBB(object):
     def __init__(self):
         srcdir = os.getcwd()
-        self.sourcetree = VCSourceTree(srcdir)
+        self.sourcetree = VCSourceTree.detect(srcdir)
+        print "sourcetree: %s" % self.sourcetree
+        print "sourcetree:", dir(self.sourcetree)
+
 
 def main(argv):
     prog = argv[0]
@@ -79,6 +138,7 @@ def main(argv):
             pass
     nbb = NBB()
 
+
 if __name__ == '__main__':
     raise "This is not a library"