Werkzeug debugger for Pylons/Paste apps

pylons_debugger.py

import pylons

from webob import Request
from paste.registry import RegistryManager
from werkzeug.debug import DebuggedApplication
from werkzeug.serving import run_simple


def pylons_controller(environ, start_response):
    1/0


def pylons_app(app):
    def wrapper(environ, start_response):
        environ['paste.registry'].register(pylons.request, Request(environ))
        return app(environ, start_response)
    return wrapper


class PylonsDebugger(object):

    def __init__(self, app):
        self.app = app
        self.debug_app = DebuggedApplication(self.catch_errors, evalex=True)
        self.cache = {}

    def catch_errors(self, environ, start_response):
        try:
            return self.app(environ, start_response)
        except Exception:
            state = environ['paste.registry'].reglist[-1]
            environ['restoration.vars'].extend(state.values())
            raise

    def __call__(self, environ, start_response):
        request = Request(environ)
        if request.GET.get('__debugger__') == 'yes':
            frm = request.GET.get('frm')
            if frm:
                frame_id = int(frm)
                if frame_id in self.cache:
                    registry = environ['paste.registry']
                    for var, obj in self.cache[frame_id]:
                        registry.register(var, obj)
                    return self.debug_app(environ, start_response)

        rest_vars = environ['restoration.vars'] = []
        old_frame_ids = list(self.debug_app.frames.keys())

        app_iter = self.debug_app(environ, start_response)
        chunks = list(app_iter)
        if hasattr(app_iter, 'close'):
            app_iter.close()

        new_frame_ids = set(self.debug_app.frames).difference(old_frame_ids)
        for frame_id in new_frame_ids:
            self.cache[frame_id] = rest_vars
        return chunks


def main():
    app = pylons_app(pylons_controller)
    app = PylonsDebugger(app)
    app = RegistryManager(app, streaming=True)
    run_simple('', 5000, app)


if __name__ == '__main__':
    main()