templating: Move common TAL methods to TALLoaderBase class

Author: techtonik

CHANGES.txt

@@ -16,6 +16,7 @@ Features:
 - Experimental proof of concept code for Jinja2 templating engine.
   Select 'jinja2' template_engine in config and place templates into 
   html/jinja2 to play with (anatoly techtonik)
+- Introducing Template Loader API (anatoly techtonik)
 
 Fixed:
 

roundup/cgi/engine_chameleon.py

@@ -5,22 +5,15 @@
 import os.path
 import chameleon
 
-from roundup.cgi.templating import StringIO, context, LoaderBase
+from roundup.cgi.templating import StringIO, context, TALLoaderBase
 
-class Loader(LoaderBase):
+class Loader(TALLoaderBase):
     def __init__(self, dir):
         self.dir = dir
         self.loader = chameleon.PageTemplateLoader(dir)
 
-    def check(self, name):
-        for extension in ['', '.html', '.xml']:
-            f = name + extension
-            src = os.path.join(self.dir, f)
-            if os.path.exists(src):
-                return (src, f)
-
     def load(self, tplname):
-        src, filename = self.check(tplname)
+        src, filename = self._find(tplname)
         return RoundupPageTemplate(self.loader.load(src))
 
 class RoundupPageTemplate(object):

roundup/cgi/engine_zopetal.py

@@ -8,29 +8,22 @@
 import os
 import os.path
 
-from roundup.cgi.templating import StringIO, context, translationService, LoaderBase
+from roundup.cgi.templating import StringIO, context, translationService, TALLoaderBase
 from roundup.cgi.PageTemplates import PageTemplate, GlobalTranslationService
 from roundup.cgi.PageTemplates.Expressions import getEngine
 from roundup.cgi.TAL import TALInterpreter
 
 GlobalTranslationService.setGlobalTranslationService(translationService)
 
-class Loader(LoaderBase):
+class Loader(TALLoaderBase):
     templates = {}
 
     def __init__(self, dir):
         self.dir = dir
 
-    def check(self, name):
-        for extension in ['', '.html', '.xml']:
-            f = name + extension
-            src = os.path.join(self.dir, f)
-            if os.path.exists(src):
-                return (src, f)
-
     def load(self, tplname):
         # find the source
-        src, filename = self.check(tplname)
+        src, filename = self._find(tplname)
 
         # has it changed?
         try:

roundup/cgi/templating.py

@@ -2,6 +2,7 @@
 """
 
 todo = """
+- Document parameters to Template.render() method
 - Add tests for Loader.load() method
 - Most methods should have a "default" arg to supply a value
   when none appears in the hyperdb or request.
@@ -88,7 +89,43 @@ def precompile(self):
         """ This method may be called when tracker is loaded to precompile
             templates that support this ability.
         """
-        # [ ] move implementation out of API
+        pass
+
+    def load(self, tplname):
+        """ Load template and return template object with render() method.
+
+            "tplname" is a template name. For filesystem loaders it is a
+            filename without extensions, typically in the "classname.view"
+            format.
+        """
+        raise NotImplementedError
+
+    def check(self, name):
+        """ Check if template with the given name exists. Should return
+            false if template can not be found.
+        """
+        raise NotImplementedError
+
+class TALLoaderBase(LoaderBase):
+    """ Common methods for the legacy TAL loaders."""
+
+    def __init__(self, dir):
+        self.dir = dir
+
+    def _find(self, name):
+        """ Find template, return full path and filename of the
+            template if it is found, None otherwise."""
+        for extension in ['', '.html', '.xml']:
+            f = name + extension
+            src = os.path.join(self.dir, f)
+            if os.path.exists(src):
+                return (src, f)
+
+    def check(self, name):
+        return bool(self._find(name))
+
+    def precompile(self):
+        """ Precompile templates in load directory by loading them """
         for filename in os.listdir(self.dir):
             # skip subdirs
             if os.path.isdir(filename):
@@ -105,24 +142,8 @@ def precompile(self):
             filename = filename[:-len(extension)]
             self.load(filename)
 
-    def load(self, tplname):
-        """ Load template and return template object with render() method.
-
-            "tplname" is a template name. For filesystem loaders it is a
-            filename without extensions, typically in the "classname.view"
-            format.
-        """
-        raise NotImplementedError
-
-    def check(self, name):
-        """ Check if template with the given name exists. Return None or
-            a tuple (src, filename) that can be reused in load() method.
-        """
-        raise NotImplementedError
-
     def __getitem__(self, name):
         """Special method to access templates by loader['name']"""
-        # [ ] not sure if it is needed for anything except TAL templates
         try:
             return self.load(name)
         except NoTemplate, message: