Source code for weblayer.bootstrap

#!/usr/bin/env python
# -*- coding: utf-8 -*-

""" :py:mod:`weblayer.bootstrap` provides :py:class:`Bootstrapper`, a helper
  class that simplifies setting up and registering :ref:`weblayer` components.
  To bootstrap a default configuration, pass a dictionary of settings
  and list of url mappings to the :py:class:`Bootstrapper` constructor::
      >>> bootstrapper = Bootstrapper(settings={}, url_mapping=[])
  Then call the ``bootstrapper`` instance to register components and get
  :py:class:`~weblayer.interfaces.ISettings` and 
  :py:class:`~weblayer.interfaces.IPathRouter` utilities.  By default, the
  bootstrapper uses :py:class:`~weblayer.settings.RequirableSettings` as its
  :py:class:`~weblayer.interfaces.ISettings` implementation and performs a 
  `venusian scan`_ of the :ref:`weblayer` package to require settings declared
  explicitly with :py:func:`~weblayer.settings.require_setting`.  This means
  that you must pass the required settings into the 
  :py:class:`Bootstrapper` constructor when instantiating the ``bootstrapper``
  or get a ``KeyError``::
      >>> settings, path_router = bootstrapper() #doctest: +NORMALIZE_WHITESPACE
      Traceback (most recent call last):
      KeyError: u'Required setting `template_directories` () is missing, 
                Required setting `static_files_path` () is missing, 
                Required setting `cookie_secret` (a long, random sequence 
                of bytes) is missing'
  Whereas if the required settings are provided, all is well::
      >>> config = {
      ...     'cookie_secret': '...', 
      ...     'static_files_path': '/var/www/static',
      ...     'template_directories': ['templates']
      ... }
      >>> bootstrapper = Bootstrapper(settings=config, url_mapping=[])
      >>> settings, path_router = bootstrapper()
  If you require your own settings (see the :py:mod:`~weblayer.settings`
  module for more information), pass in the dotted names of the modules
  or packages they are required in::
      >>> bootstrapper = Bootstrapper(settings=config, url_mapping=[])
      >>> settings, path_router = bootstrapper(packages=['foo', ''])
      Traceback (most recent call last):
      ImportError: No module named foo
  To override specific components, either pass in ``False`` to skip
  registering them, e.g.::
      >>> bootstrapper = Bootstrapper(settings=config, url_mapping=[])
      >>> settings, path_router = bootstrapper(TemplateRenderer=False)
  Or pass in your own implementation, e.g.::
      >>> from mock import Mock
      >>> mock_router = Mock()
      >>> bootstrapper = Bootstrapper(settings=config, url_mapping=[])
      >>> settings, path_router = bootstrapper(path_router=mock_router)
      >>> path_router == mock_router
  .. _`venusian scan`:

__all__ = [

import imp
import sys

from os.path import dirname
from pkgutil import iter_modules

from component import registry
from interfaces import *

from auth import TrivialAuthenticationManager
from cookie import SignedSecureCookieWrapper
from method import ExposedMethodSelector
from normalise import DefaultToJSONResponseNormaliser
from route import RegExpPathRouter
from settings import RequirableSettings
from static import MemoryCachedStaticURLGenerator
from template import MakoTemplateRenderer

[docs]class Bootstrapper(object): """ Simplifies setting up and registering :ref:`weblayer` components. """ def __init__(self, settings=None, url_mapping=None): """ Stores the ``settings`` and ``url_mapping`` provided:: >>> config = {'a': 'b'} >>> mapping = [()] >>> b = Bootstrapper(settings=config, url_mapping=mapping) >>> b._user_settings {'a': 'b'} >>> b._url_mapping [()] """ if settings is None: self._user_settings = {} else: self._user_settings = settings if url_mapping is None: self._url_mapping = [] else: self._url_mapping = url_mapping
[docs] def __call__( self, packages=None, scan_framework=True, extra_categories=None, require_settings=True, **kwargs ): """ If ``require_settings`` is ``True`` and ``settings`` isn't provided as a keyword argument, call :py:meth:`require_settings`, :py:meth:`register_components` and return ``settings, path_router``. """ if 'settings' in kwargs or not require_settings: settings_component = kwargs.get('settings', None) else: settings_component = self.require_settings( packages=packages, scan_framework=scan_framework, extra_categories=extra_categories ) kwargs['settings'] = settings_component self.register_components(**kwargs) settings = registry.getUtility(ISettings) path_router = registry.getUtility(IPathRouter) return settings, path_router
[docs] def require_settings( self, packages=None, scan_framework=True, extra_categories=None ): """ Init and return a :py:class:`~weblayer.settings.RequirableSettings` instance, scanning ``packages`` for required settings. """ if packages is None: packages = [] framework_modules = [] if scan_framework: # only scan (non-orphaned) source files, in order to avoid scanning # tests and examples path = dirname(__file__) for importer, modname, ispkg in iter_modules([path], 'weblayer.'): loader = importer.find_module(modname) module_type = loader.etc[2] if module_type == imp.PY_SOURCE: framework_modules.append(modname) to_scan = [] for item in framework_modules + packages: if not item in sys.modules: # pragma: no coverage __import__(item) to_scan.append(sys.modules[item]) settings = RequirableSettings( packages=to_scan, extra_categories=extra_categories ) return settings
[docs] def register_components( self, settings=None, path_router=None, TemplateRenderer=None, AuthenticationManager=None, SecureCookieWrapper=None, StaticURLGenerator=None, MethodSelector=None, ResponseNormaliser=None ): """ Setup component registrations. Pass in alternative implementations here to override, or pass in ``False`` to avoid registering a component. """ if settings is not False: if settings is None: settings = RequirableSettings() settings(self._user_settings) registry.registerUtility(settings, ISettings) if path_router is not False: if path_router is None: path_router = RegExpPathRouter(self._url_mapping) registry.registerUtility(path_router, IPathRouter) if TemplateRenderer is not False: if TemplateRenderer is None: TemplateRenderer = MakoTemplateRenderer registry.registerAdapter( TemplateRenderer, required=[ISettings], provided=ITemplateRenderer ) if AuthenticationManager is not False: if AuthenticationManager is None: AuthenticationManager = TrivialAuthenticationManager registry.registerAdapter( AuthenticationManager, required=[IRequest], provided=IAuthenticationManager ) if StaticURLGenerator is not False: if StaticURLGenerator is None: StaticURLGenerator = MemoryCachedStaticURLGenerator registry.registerAdapter( StaticURLGenerator, required=[IRequest, ISettings], provided=IStaticURLGenerator ) if SecureCookieWrapper is not False: if SecureCookieWrapper is None: SecureCookieWrapper = SignedSecureCookieWrapper registry.registerAdapter( SecureCookieWrapper, required=[IRequest, IResponse, ISettings], provided=ISecureCookieWrapper ) if MethodSelector is not False: if MethodSelector is None: MethodSelector = ExposedMethodSelector registry.registerAdapter( MethodSelector, required=[IRequestHandler], provided=IMethodSelector ) if ResponseNormaliser is not False: if ResponseNormaliser is None: ResponseNormaliser = DefaultToJSONResponseNormaliser registry.registerAdapter( ResponseNormaliser, required=[IResponse], provided=IResponseNormaliser )