StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

POEncapsulation with __getattr__ and related
text
Body
copied!<p>I'm trying to encapsulate an object without changing it's default behavior, the problem is that by the time I get access to the object it's already constructed. As such, my idea is to use inheritance and use <code>__getattr__</code>, <code>__setattr__</code>, <code>__getitem__</code>, and <code>__setitem__</code> and delegate to the encapsulated object, except for fields I define myself.</p> <pre><code>class Request(HttpRequest): def __init__(self, request, *args, **kwargs): self._original_request = request super(Request, self).__init__(*args, **kwargs) def __getattr__(self, name): return getattr(self._original_request, name) def __setattr__(self, name, value): if name == '_original_request': super(Request, self).__setattr__(name, value) else: self._original_request.__setattr__(name, value) def __getitem__(self, key): return self._original_request[key] def __setitem__(self, key, value): self._original_request[key] = value </code></pre> <p>If I pass along the original object, everything is fine. If I don't, I get</p> <pre><code>host = self.META['SERVER_NAME'] KeyError: u'SERVER_NAME' </code></pre> <p>Am I missing something? Shouldn't my class behave exactly that the one it encapsulates?</p> <pre><code>Internal Server Error: / Traceback (most recent call last): File "c:\Python27\lib\site-packages\django\core\handlers\base.py", line 115, in get_response response = callback(request, *callback_args, **callback_kwargs) File "c:\Python27\lib\site-packages\django\views\generic\base.py", line 68, in view return self.dispatch(request, *args, **kwargs) File "C:\www\lookwanted\djutils\views.py", line 35, in dispatch return super(View, self).dispatch(Request(request), *args, **kwargs) File "C:\www\lookwanted\djutils\views.py", line 12, in __init__ super(Request, self).__init__(*args, **kwargs) File "c:\Python27\lib\site-packages\django\http\request.py", line 43, in __init__ self.GET, self.POST, self.COOKIES, self.META, self.FILES = {}, {}, {}, {}, {} File "C:\www\lookwanted\djutils\views.py", line 21, in __setattr__ self._original_request.__setattr__(name, value) AttributeError: can't set attribute Traceback (most recent call last): File "c:\Python27\lib\wsgiref\handlers.py", line 85, in run self.result = application(self.environ, self.start_response) File "c:\Python27\lib\site-packages\django\contrib\staticfiles\handlers.py", line 72, in __call__ return self.application(environ, start_response) File "c:\Python27\lib\site-packages\django\core\handlers\wsgi.py", line 255, in __call__ response = self.get_response(request) File "c:\Python27\lib\site-packages\django\core\handlers\base.py", line 178, in get_response response = self.handle_uncaught_exception(request, resolver, sys.exc_info()) File "c:\Python27\lib\site-packages\django\core\handlers\base.py", line 217, in handle_uncaught_exception return debug.technical_500_response(request, *exc_info) File "c:\Python27\lib\site-packages\django\views\debug.py", line 69, in technical_500_response html = reporter.get_traceback_html() File "c:\Python27\lib\site-packages\django\views\debug.py", line 298, in get_traceback_html return t.render(c) File "c:\Python27\lib\site-packages\django\template\base.py", line 140, in render return self._render(context) File "c:\Python27\lib\site-packages\django\template\base.py", line 134, in _render return self.nodelist.render(context) File "c:\Python27\lib\site-packages\django\template\base.py", line 830, in render bit = self.render_node(node, context) File "c:\Python27\lib\site-packages\django\template\debug.py", line 74, in render_node return node.render(context) File "c:\Python27\lib\site-packages\django\template\defaulttags.py", line 284, in render return nodelist.render(context) File "c:\Python27\lib\site-packages\django\template\base.py", line 830, in render bit = self.render_node(node, context) File "c:\Python27\lib\site-packages\django\template\debug.py", line 74, in render_node return node.render(context) File "c:\Python27\lib\site-packages\django\template\debug.py", line 84, in render output = self.filter_expression.resolve(context) File "c:\Python27\lib\site-packages\django\template\base.py", line 578, in resolve obj = self.var.resolve(context) File "c:\Python27\lib\site-packages\django\template\base.py", line 728, in resolve value = self._resolve_lookup(context) File "c:\Python27\lib\site-packages\django\template\base.py", line 779, in _resolve_lookup current = current() File "c:\Python27\lib\site-packages\django\http\request.py", line 112, in build_absolute_uri self.get_host(), self.path) File "c:\Python27\lib\site-packages\django\http\request.py", line 62, in get_host host = self.META['SERVER_NAME'] KeyError: u'SERVER_NAME' </code></pre>

Querying!

Guidance

An individual column

Larger individual text columns get their own page to allow for proper reading.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload