various docstring changes

--HG--
branch : trunk
diff --git a/jinja2/compiler.py b/jinja2/compiler.py
index ca25304..596091e 100644
--- a/jinja2/compiler.py
+++ b/jinja2/compiler.py
@@ -424,7 +424,7 @@
             raise TemplateAssertionError('It\'s not possible to set and '
                                          'access variables derived from '
                                          'an outer scope! (affects: %s' %
-                                         vars, node.lineno, self.filename)
+                                         vars, node.lineno, self.name)
 
         # remove variables from a closure from the frame's undeclared
         # identifiers.
@@ -463,7 +463,7 @@
             if block.name in self.blocks:
                 raise TemplateAssertionError('block %r defined twice' %
                                              block.name, block.lineno,
-                                             self.filename)
+                                             self.name)
             self.blocks[block.name] = block
 
         # generate the root render function.
@@ -545,7 +545,7 @@
         if not frame.toplevel:
             raise TemplateAssertionError('cannot use extend from a non '
                                          'top-level scope', node.lineno,
-                                         self.filename)
+                                         self.name)
 
         # if the number of extends statements in general is zero so
         # far, we don't have to add a check if something extended
@@ -570,7 +570,7 @@
 
         self.writeline('parent_root = environment.get_template(', node, 1)
         self.visit(node.template, frame)
-        self.write(', %r).root_render_func' % self.filename)
+        self.write(', %r).root_render_func' % self.name)
 
         # if this extends statement was in the root level we can take
         # advantage of that information and simplify the generated code
diff --git a/jinja2/environment.py b/jinja2/environment.py
index 9fdfdae..4b1e70c 100644
--- a/jinja2/environment.py
+++ b/jinja2/environment.py
@@ -132,7 +132,12 @@
 
     def compile(self, source, name=None, filename=None, raw=False,
                 globals=None):
-        """Compile a node or source."""
+        """Compile a node or source.  The name is the load name of the
+        template after it was joined using `join_path` if necessary,
+        filename is the estimated filename of the template on the file
+        system.  If the template came from a database or memory this
+        can be omitted.
+        """
         if isinstance(source, basestring):
             source = self.parse(source, name)
         if self.optimized:
@@ -141,7 +146,7 @@
         if raw:
             return source
         if filename is None:
-            filename = '<from_string>'
+            filename = '<template>'
         elif isinstance(filename, unicode):
             filename = filename.encode('utf-8')
         return compile(source, filename, 'exec')
diff --git a/jinja2/exceptions.py b/jinja2/exceptions.py
index f07d860..024ff58 100644
--- a/jinja2/exceptions.py
+++ b/jinja2/exceptions.py
@@ -24,23 +24,23 @@
         self.name = name
 
 
-class TemplateSyntaxError(SyntaxError, TemplateError):
+class TemplateSyntaxError(TemplateError):
     """
     Raised to tell the user that there is a problem with the template.
     """
 
-    def __init__(self, message, lineno, filename):
-        SyntaxError.__init__(self, '%s (line %s)' % (message, lineno))
+    def __init__(self, message, lineno, name):
+        TEmplateError.__init__(self, '%s (line %s)' % (message, lineno))
         self.message = message
         self.lineno = lineno
-        self.filename = filename
+        self.name = name
 
 
 class TemplateAssertionError(AssertionError, TemplateSyntaxError):
 
-    def __init__(self, message, lineno, filename):
+    def __init__(self, message, lineno, name):
         AssertionError.__init__(self, message)
-        TemplateSyntaxError.__init__(self, message, lineno, filename)
+        TemplateSyntaxError.__init__(self, message, lineno, name)
 
 
 class TemplateRuntimeError(TemplateError):
diff --git a/jinja2/runtime.py b/jinja2/runtime.py
index 2b05e73..a18b7bc 100644
--- a/jinja2/runtime.py
+++ b/jinja2/runtime.py
@@ -26,11 +26,11 @@
     the exported variables for example).
     """
 
-    def __init__(self, environment, globals, filename, blocks, standalone):
+    def __init__(self, environment, globals, name, blocks, standalone):
         dict.__init__(self, globals)
         self.environment = environment
         self.exported = set()
-        self.filename = filename
+        self.name = name
         self.blocks = dict((k, [v]) for k, v in blocks.iteritems())
 
         # if the template is in standalone mode we don't copy the blocks over.
@@ -74,7 +74,7 @@
         return '<%s %s of %r>' % (
             self.__class__.__name__,
             dict.__repr__(self),
-            self.filename
+            self.name
         )
 
 
@@ -103,7 +103,7 @@
         template = environment.get_template(template)
         gen = template.root_render_func(context, standalone=True)
         context = gen.next()
-        self._filename = template.name
+        self._name = template.name
         self._rendered_body = u''.join(gen)
         self._context = context.get_exported()
 
@@ -119,7 +119,7 @@
     def __repr__(self):
         return '<%s %r>' % (
             self.__class__.__name__,
-            self._filename
+            self._name
         )
 
 
diff --git a/jinja2/utils.py b/jinja2/utils.py
index 2e64fe2..63394ce 100644
--- a/jinja2/utils.py
+++ b/jinja2/utils.py
@@ -16,7 +16,9 @@
 
 def escape(obj, attribute=False):
     """HTML escape an object."""
-    if hasattr(obj, '__html__'):
+    if obj is None:
+        return u''
+    elif hasattr(obj, '__html__'):
         return obj.__html__()
     return Markup(unicode(obj)
         .replace('&', '&amp;')