added TemplateHelper plugin to easily provide convenience methods to templates

2 files changed, 86 insertions, 2 deletions

diff --git a/src/lib/Server/Plugin.py b/src/lib/Server/Plugin.py
index 06de18f29..c48859a44 100644
--- a/src/lib/Server/Plugin.py
+++ b/src/lib/Server/Plugin.py
@@ -935,7 +935,7 @@ class SpecificData(object):
             logger.error("Failed to read file %s" % self.name)
 
 
-class EntrySet:
+class EntrySet(object):
     """Entry sets deal with the host- and group-specific entries."""
     ignore = re.compile("^(\.#.*|.*~|\\..*\\.(sw[px])|.*\\.genshi_include)$")
 
@@ -1011,7 +1011,8 @@ class EntrySet:
                 spec = self.specificity_from_filename(event.filename)
             except SpecificityError:
                 if not self.ignore.match(event.filename):
-                    logger.error("Could not process filename %s; ignoring" % fpath)
+                    logger.error("Could not process filename %s; ignoring" %
+                                 fpath)
                 return
             self.entries[event.filename] = self.entry_type(fpath,
                                                            spec, self.encoding)
diff --git a/src/lib/Server/Plugins/TemplateHelper.py b/src/lib/Server/Plugins/TemplateHelper.py
new file mode 100644
index 000000000..42eafed56
--- /dev/null
+++ b/src/lib/Server/Plugins/TemplateHelper.py
@@ -0,0 +1,83 @@
+import re
+import imp
+import sys
+import logging
+import Bcfg2.Server.Plugin
+
+logger = logging.getLogger(__name__)
+
+class HelperModule(Bcfg2.Server.Plugin.SpecificData):
+    _module_name_re = re.compile(r'([^/]+?)\.py')
+    
+    def __init__(self, name, specific, encoding):
+        Bcfg2.Server.Plugin.SpecificData.__init__(self, name, specific,
+                                                  encoding)
+        match = self._module_name_re.search(self.name)
+        if match:
+            self._module_name = match.group(1)
+        else:
+            self._module_name = name
+        self._attrs = []
+        
+    def handle_event(self, event):
+        Bcfg2.Server.Plugin.SpecificData.handle_event(self, event)
+        try:
+            module = imp.load_source(self._module_name, self.name)
+        except:
+            err = sys.exc_info()[1]
+            logger.error("TemplateHelper: Failed to import %s: %s" %
+                         (self.name, err))
+            return
+
+        if not hasattr(module, "__export__"):
+            logger.error("TemplateHelper: %s has no __export__ list" %
+                         self.name)
+            return
+
+        for sym in module.__export__:
+            if sym not in self._attrs and hasattr(self, sym):
+                logger.warning("TemplateHelper: %s: %s is a reserved keyword, "
+                               "skipping export" % (self.name, sym))
+            setattr(self, sym, getattr(module, sym))
+        # remove old exports
+        for sym in set(self._attrs) - set(module.__export__):
+            delattr(self, sym)
+            
+        self._attrs = module.__export__
+        
+
+class HelperSet(Bcfg2.Server.Plugin.EntrySet):
+    ignore = re.compile("^(\.#.*|.*~|\\..*\\.(sw[px])|.*\.py[co])$")
+    
+    def __init__(self, path, fam, encoding, plugin_name):
+        fpattern = '[0-9A-Za-z_\-]+\.py'
+        self.plugin_name = plugin_name
+        Bcfg2.Server.Plugin.EntrySet.__init__(self, fpattern, path,
+                                              HelperModule, encoding)
+        fam.AddMonitor(path, self)
+
+    def HandleEvent(self, event):
+        if (event.filename != self.path and
+            not self.ignore.match(event.filename)):
+            return self.handle_event(event)
+
+
+class TemplateHelper(Bcfg2.Server.Plugin.Plugin,
+                     Bcfg2.Server.Plugin.Connector):
+    """ A plugin to provide helper classes and functions to templates """
+    name = 'TemplateHelper'
+    __author__ = 'chris.a.st.pierre@gmail.com'
+
+    def __init__(self, core, datastore):
+        Bcfg2.Server.Plugin.Plugin.__init__(self, core, datastore)
+        Bcfg2.Server.Plugin.Connector.__init__(self)
+
+        try:
+            self.helpers = HelperSet(self.data, core.fam, core.encoding,
+                                     self.name)
+        except:
+            raise Bcfg2.Server.Plugin.PluginInitError
+
+    def get_additional_data(self, metadata):
+        return dict([(h._module_name, h)
+                     for h in list(self.helpers.entries.values())])