From ca144dae2ae4221c1051351e7e219ab1618e8d20 Mon Sep 17 00:00:00 2001
From: Armin Ronacher <armin.ronacher@active-4.com>
Date: Tue, 20 Mar 2007 17:35:07 +0100
Subject: [PATCH] [svn] added a loader that loads templates from functions
 provided

--HG--
branch : trunk
---
 jinja/loaders.py | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 jinja/utils.py   |  2 +-
 2 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/jinja/loaders.py b/jinja/loaders.py
index 6901b40..ff701a9 100644
--- a/jinja/loaders.py
+++ b/jinja/loaders.py
@@ -25,7 +25,8 @@ except ImportError:
     resource_exists = resource_string = resource_filename = None
 
 
-__all__ = ['FileSystemLoader', 'PackageLoader', 'DictLoader', 'ChoiceLoader']
+__all__ = ['FileSystemLoader', 'PackageLoader', 'DictLoader', 'ChoiceLoader',
+           'FunctionLoader']
 
 
 def get_template_filename(searchpath, name):
@@ -333,6 +334,48 @@ class PackageLoader(CachedLoaderMixin, BaseLoader):
         return 0
 
 
+class FunctionLoader(CachedLoaderMixin, BaseLoader):
+    """
+    Loads templates by calling a function which has to return a string
+    or `None` if an error occoured.
+
+    .. sourcecode:: python
+
+        from jinja import Environment, FunctionLoader
+
+        def my_load_func(template_name):
+            if template_name == 'foo':
+                return '...'
+
+        e = Environment(loader=FunctionLoader(my_load_func))
+
+    Because the interface is limited there is no way to cache such
+    templates. Usually you should try to use a loader with a more
+    solid backend.
+
+    You can pass the following keyword arguments to the loader on
+    initialisation:
+
+    =================== =================================================
+    ``loader_func``     Function that takes the name of the template to
+                        load. If it returns a string or unicode object
+                        it's used to load a template. If the return
+                        value is None it's considered missing.
+    =================== =================================================
+    """
+
+    def __init__(self, loader_func):
+        self.loader_func = loader_func
+
+    def get_source(self, environment, name, parent):
+        rv = self.loader_func(name)
+        if rv is None:
+            raise TemplateNotFound(name)
+        if isinstance(rv, str):
+            return rv.decode(environment.template_charset)
+        return rv
+
+
 class DictLoader(BaseLoader):
     """
     Load templates from a given dict:
diff --git a/jinja/utils.py b/jinja/utils.py
index 4646d1d..c561da7 100644
--- a/jinja/utils.py
+++ b/jinja/utils.py
@@ -164,7 +164,7 @@ def buffereater(f):
 def raise_template_exception(exception, filename, lineno, context):
     """
     Raise an exception "in a template". Return a traceback
-    object.
+    object. This is used for runtime debugging, not compile time.
     """
     # some traceback systems allow to skip frames
     __traceback_hide__ = True
-- 
2.26.2