django1/django/template/context.py

98 lines
3.2 KiB
Python

from django.conf import settings
from django.core.exceptions import ImproperlyConfigured
_standard_context_processors = None
class ContextPopException(Exception):
"pop() has been called more times than push()"
pass
class Context(object):
"A stack container for variable context"
def __init__(self, dict_=None):
dict_ = dict_ or {}
self.dicts = [dict_]
def __repr__(self):
return repr(self.dicts)
def __iter__(self):
for d in self.dicts:
yield d
def push(self):
self.dicts = [{}] + self.dicts
def pop(self):
if len(self.dicts) == 1:
raise ContextPopException
del self.dicts[0]
def __setitem__(self, key, value):
"Set a variable in the current context"
self.dicts[0][key] = value
def __getitem__(self, key):
"Get a variable's value, starting at the current context and going upward"
for d in self.dicts:
if d.has_key(key):
return d[key]
raise KeyError(key)
def __delitem__(self, key):
"Delete a variable from the current context"
del self.dicts[0][key]
def has_key(self, key):
for d in self.dicts:
if d.has_key(key):
return True
return False
def get(self, key, otherwise=None):
for d in self.dicts:
if d.has_key(key):
return d[key]
return otherwise
def update(self, other_dict):
"Like dict.update(). Pushes an entire dictionary's keys and values onto the context."
self.dicts = [other_dict] + self.dicts
# This is a function rather than module-level procedural code because we only
# want it to execute if somebody uses RequestContext.
def get_standard_processors():
global _standard_context_processors
if _standard_context_processors is None:
processors = []
for path in settings.TEMPLATE_CONTEXT_PROCESSORS:
i = path.rfind('.')
module, attr = path[:i], path[i+1:]
try:
mod = __import__(module, '', '', [attr])
except ImportError, e:
raise ImproperlyConfigured, 'Error importing request processor module %s: "%s"' % (module, e)
try:
func = getattr(mod, attr)
except AttributeError:
raise ImproperlyConfigured, 'Module "%s" does not define a "%s" callable request processor' % (module, attr)
processors.append(func)
_standard_context_processors = tuple(processors)
return _standard_context_processors
class RequestContext(Context):
"""
This subclass of template.Context automatically populates itself using
the processors defined in TEMPLATE_CONTEXT_PROCESSORS.
Additional processors can be specified as a list of callables
using the "processors" keyword argument.
"""
def __init__(self, request, dict=None, processors=None):
Context.__init__(self, dict)
if processors is None:
processors = ()
else:
processors = tuple(processors)
for processor in get_standard_processors() + processors:
self.update(processor(request))