Added support for accessing template context.

README.rst

@@ -111,6 +111,27 @@ Produces:
 
 Oh no, it's already February 20th, 2010!
 
+Accessing the Template Context
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Python Code::
+
+    @fancy_tag(register, takes_context)
+    def say_hello_to_user(context, phrase):
+        return u'%s, %s!' % (phrase, context['user'])
+
+Template Context::
+
+    {'user': 'Tobias'}  # Provided by a template context processor, for example
+
+Template Code::
+
+    {% say_hello_to_user "Hallo" %}
+
+Produces:
+
+Hallo, Tobias!
+
 Testing
 -------
 

fancy_tag/__init__.py

@@ -8,10 +8,18 @@
 kwarg_re = re.compile(r'([^\'"]*)=(.*)')
 
 
-def fancy_tag_compiler(params, defaults, takes_var_args, takes_var_kwargs, name, node_class, parser, token):
+def fancy_tag_compiler(params, defaults, takes_var_args, takes_var_kwargs, takes_context, name, node_class, parser, token):
     "Returns a template.Node subclass."
     bits = token.split_contents()[1:]
 
+    if takes_context:
+        if 'context' in params[:1]:
+            params = params[1:]
+        else:
+            raise TemplateSyntaxError(
+                "Any tag function decorated with takes_context=True "
+                "must have a first argument of 'context'")
+
     # Split args and kwargs
     args = []
     kwargs = {}
@@ -56,25 +64,29 @@ def fancy_tag_compiler(params, defaults, takes_var_args, takes_var_kwargs, name,
         raise TemplateSyntaxError("%s didn't get values for arguments: %s" % (
                 name, ', '.join(["'%s'" % p for p in unhandled_params])))
 
-    return node_class(args, kwargs, output_var)
+    return node_class(args, kwargs, output_var, takes_context)
 
 
-def fancy_tag(library):
+def fancy_tag(library, takes_context=False):
     def inner(func):
         params, var_args_var, var_kwargs_var, defaults = getargspec(func)
 
         class FancyNode(Node):
-            def __init__(self, vars_to_resolve, kw_vars_to_resolve, output_var):
+            def __init__(self, vars_to_resolve, kw_vars_to_resolve, output_var, takes_context):
                 self.vars_to_resolve = map(Variable, vars_to_resolve)
                 self.kw_vars_to_resolve = dict(
                         [(kw, Variable(var)) for kw, var in kw_vars_to_resolve.items()])
                 self.output_var = output_var
+                self.takes_context = takes_context
 
             def render(self, context):
                 args = [var.resolve(context) for var in self.vars_to_resolve]
                 kwargs = dict(
                         [(kw, var.resolve(context)) for kw, var in self.kw_vars_to_resolve.items()])
 
+                if self.takes_context:
+                    args = [context] + args
+
                 if self.output_var is not None:
                     context[self.output_var] = func(*args, **kwargs)
                     return ''
@@ -87,6 +99,7 @@ def render(self, context):
                 defaults,
                 var_args_var is not None,
                 var_kwargs_var is not None,
+                takes_context,
                 getattr(func, "_decorated_function", func).__name__,
                 FancyNode
                 )

tests/test_app/templatetags/example_tags.py

@@ -25,3 +25,14 @@ def say_names(*args):
 @fancy_tag(register)
 def say_languages(**kwargs):
     return ', '.join(['%s: %s' % (kw, v) for kw, v in kwargs.items()])
+
+
+@fancy_tag(register, takes_context=True)
+def say_hello(context, greeting):
+    return u'%s, %s' % (greeting, context['user'])
+
+
+@fancy_tag(register, takes_context=True)
+def say_hello_like_a_chump(greeting):
+    # Broken on purpose
+    return u'%s, %s' % (greeting, context['?'])

tests/test_app/tests.py

@@ -85,3 +85,14 @@ def testBadAsVarFails(self):
                 Template,
                 '{% load example_tags %}{% say_soup "Stone" as "bad var name" %}'
                 )
+
+    def testTakesContext(self):
+        template = Template('{% load example_tags %}{% say_hello "Hallo" %}')
+        self.assertEqual(template.render(Context({'user': 'Tobias'})), 'Hallo, Tobias')
+
+    def testTakesContextOnFuncThatDoesNotTakeContextFails(self):
+        self.assertRaises(
+                TemplateSyntaxError,
+                Template,
+                '{% load example_tags %}{% say_hello_like_a_chump "Hallo" %}'
+                )