Fixed #625 -- Added template-tag decorators simple_tag and inclusion_tag. Taken from new-admin. Thanks, rjwittams

git-svn-id: http://code.djangoproject.com/svn/django/trunk@1410 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/template/decorators.py

@@ -0,0 +1,67 @@
+from django.core.template import Context, Node, TemplateSyntaxError, register_tag, resolve_variable
+from django.core.template_loader import get_template
+from django.utils.functional import curry
+from inspect import getargspec
+
+def generic_tag_compiler(params, defaults, name, node_class, parser, token):
+    "Returns a template.Node subclass."
+    bits = token.contents.split()[1:]
+    bmax = len(params)
+    def_len = defaults and len(defaults) or 0
+    bmin = bmax - def_len
+    if(len(bits) < bmin or len(bits) > bmax):
+        if bmin == bmax:
+            message = "%s takes %s arguments" % (name, bmin)
+        else:
+            message = "%s takes between %s and %s arguments" % (name, bmin, bmax)
+        raise TemplateSyntaxError, message
+    return node_class(bits)
+
+def simple_tag(func):
+    (params, xx, xxx, defaults) = getargspec(func)
+
+    class SimpleNode(Node):
+        def __init__(self, vars_to_resolve):
+            self.vars_to_resolve = vars_to_resolve
+
+        def render(self, context):
+            resolved_vars = [resolve_variable(var, context) for var in self.vars_to_resolve]
+            return func(*resolved_vars)
+
+    compile_func = curry(generic_tag_compiler, params, defaults, func.__name__, SimpleNode)
+    compile_func.__doc__ = func.__doc__
+    register_tag(func.__name__, compile_func)
+    return func
+
+def inclusion_tag(file_name, context_class=Context, takes_context=False):
+    def dec(func):
+        (params, xx, xxx, defaults) = getargspec(func)
+        if takes_context:
+            if params[0] == 'context':
+                params = params[1:]
+            else:
+                raise TemplateSyntaxError, "Any tag function decorated with takes_context=True must have a first argument of 'context'"
+
+        class InclusionNode(Node):
+            def __init__(self, vars_to_resolve):
+                self.vars_to_resolve = vars_to_resolve
+
+            def render(self, context):
+                resolved_vars = [resolve_variable(var, context) for var in self.vars_to_resolve]
+                if takes_context:
+                    args = [context] + resolved_vars
+                else:
+                    args = resolved_vars
+
+                dict = func(*args)
+
+                if not getattr(self, 'nodelist', False):
+                    t = get_template(file_name)
+                    self.nodelist = t.nodelist
+                return self.nodelist.render(context_class(dict))
+
+        compile_func = curry(generic_tag_compiler, params, defaults, func.__name__, InclusionNode)
+        compile_func.__doc__ = func.__doc__
+        register_tag(func.__name__, compile_func)
+        return func
+    return dec