一可以借鑒的地方
1、單例模式
配置文件的引入：減少了開辟空間，其他好處想到了再補充
2、用戶組或用戶權限獲取時調用了一個方法（簡單工廠方法模式）
調用的防范並沒有使用if判斷而是使用了反射，擴展性較好
3、利用文件夾中init文件
二、源碼研究
1、找到項目中的代碼及進入方法內部
user = request.user
if user.has_perm('check')
2、源碼的執行的主流程
1、裝飾器的執行
def new_method_proxy(func):
def inner(self, *args):
if self._wrapped is empty: #user中的_wrapped一般不為empty
self._setup()
return func(self._wrapped, *args)
return inner
class PermissionsMixin(models.Model):
"""
A mixin class that adds the fields and methods necessary to support
Django's Group and Permission model using the ModelBackend.
"""
is_superuser = models.BooleanField(_('superuser status'), default=False,
help_text=_('Designates that this user has all permissions without '
'explicitly assigning them.'))
groups = models.ManyToManyField(Group, verbose_name=_('groups'),
blank=True, help_text=_('The groups this user belongs to. A user will '
'get all permissions granted to each of '
'their groups.'),
related_name="user_set", related_query_name="user")
user_permissions = models.ManyToManyField(Permission,
verbose_name=_('user permissions'), blank=True,
help_text=_('Specific permissions for this user.'),
related_name="user_set", related_query_name="user")
class Meta:
abstract = True
def get_group_permissions(self, obj=None):
"""
Returns a list of permission strings that this user has through their
groups. This method queries all available auth backends. If an object
is passed in, only permissions matching this object are returned.
"""
permissions = set()
for backend in auth.get_backends():
if hasattr(backend, "get_group_permissions"):
permissions.update(backend.get_group_permissions(self, obj))
return permissions
def get_all_permissions(self, obj=None):
return _user_get_all_permissions(self, obj)
2、執行has_perm self：user perm: 'check'
def has_perm(self, perm, obj=None):
"""
Returns True if the user has the specified permission. This method
queries all available auth backends, but returns immediately if any
backend returns True. Thus, a user who has permission from a single
auth backend is assumed to have permission in general. If an object is
provided, permissions for this specific object are checked.
"""
# Active superusers have all permissions.
if self.is_active and self.is_superuser:
return True
# Otherwise we need to check the backends.
return _user_has_perm(self, perm, obj)
def has_perms(self, perm_list, obj=None):
"""
Returns True if the user has each of the specified permissions. If
object is passed, it checks if the user has all required perms for this
object.
"""
for perm in perm_list:
if not self.has_perm(perm, obj):
return False
return True
def has_module_perms(self, app_label):
"""
Returns True if the user has any permissions in the given app label.
Uses pretty much the same logic as has_perm, above.
"""
# Active superusers have all permissions.
if self.is_active and self.is_superuser:
return True
return _user_has_module_perms(self, app_label)
3、執行 self：user perm: 'financial_flow.flow_financial' obj=None
def _user_has_perm(user, perm, obj):
"""
A backend can raise `PermissionDenied` to short-circuit permission checking.
"""
# shi3-1:實例化 backend
for backend in auth.get_backends():
if not hasattr(backend, 'has_perm'):
continue
try:
if backend.has_perm(user, perm, obj):
return True
except PermissionDenied:
return False
return False
4、backend 類中has_perm方法的執行
class ModelBackend(object):
"""
Authenticates against settings.AUTH_USER_MODEL.
"""
def authenticate(self, username=None, password=None, **kwargs):
UserModel = get_user_model()
if username is None:
username = kwargs.get(UserModel.USERNAME_FIELD)
try:
user = UserModel._default_manager.get_by_natural_key(username)
if user.check_password(password):
return user
except UserModel.DoesNotExist:
# Run the default password hasher once to reduce the timing
# difference between an existing and a non-existing user (#20760).
UserModel().set_password(password)
#4-2-4 獲取用戶的特殊權限
def _get_user_permissions(self, user_obj):
return user_obj.user_permissions.all()
#4-3-4獲取用戶組特殊權限
def _get_group_permissions(self, user_obj):
user_groups_field = get_user_model()._meta.get_field('groups')
user_groups_query = 'group__%s' % user_groups_field.related_query_name()
return Permission.objects.filter(**{user_groups_query: user_obj})
#4-2-2 獲取用戶的特殊權限
#4-3-2獲取用戶組特殊權限
def _get_permissions(self, user_obj, obj, from_name): #from_name user
"""
Returns the permissions of `user_obj` from `from_name`. `from_name` can
be either "group" or "user" to return permissions from
`_get_group_permissions` or `_get_user_permissions` respectively.
"""
if not user_obj.is_active or user_obj.is_anonymous() or obj is not None:
return set()
perm_cache_name = '_%s_perm_cache' % from_name #u'_user_perm_cache'
if not hasattr(user_obj, perm_cache_name):
if user_obj.is_superuser:
perms = Permission.objects.all()
else:
#4-2-3 獲取用戶的特殊權限
#4-3-3獲取用戶組特殊權限
perms = getattr(self, '_get_%s_permissions' % from_name)(user_obj) #_get_user_permissions
perms = perms.values_list('content_type__app_label', 'codename').order_by()
setattr(user_obj, perm_cache_name, set("%s.%s" % (ct, name) for ct, name in perms))
return getattr(user_obj, perm_cache_name)
#4-2-1獲取用戶的特殊權限
def get_user_permissions(self, user_obj, obj=None):
"""
Returns a set of permission strings the user `user_obj` has from their
`user_permissions`.
"""
return self._get_permissions(user_obj, obj, 'user')
#4-3-1獲取用戶組特殊權限
def get_group_permissions(self, user_obj, obj=None):
"""
Returns a set of permission strings the user `user_obj` has from the
groups they belong.
"""
return self._get_permissions(user_obj, obj, 'group')
#4-1獲取所有的權限
def get_all_permissions(self, user_obj, obj=None):
if not user_obj.is_active or user_obj.is_anonymous() or obj is not None:
return set()
if not hasattr(user_obj, '_perm_cache'):
#4-2 獲取用戶的特殊權限
user_obj._perm_cache = self.get_user_permissions(user_obj)
#4-3 獲取用戶所屬組的特殊群限
user_obj._perm_cache.update(self.get_group_permissions(user_obj))
return user_obj._perm_cache
def has_perm(self, user_obj, perm, obj=None):
if not user_obj.is_active:
return False
#4-1獲取所有的權限
return perm in self.get_all_permissions(user_obj, obj) #結果就是True或False
def has_module_perms(self, user_obj, app_label):
"""
Returns True if user_obj has any permissions in the given app_label.
"""
if not user_obj.is_active:
return False
for perm in self.get_all_permissions(user_obj):
if perm[:perm.index('.')] == app_label:
return True
return False
def get_user(self, user_id):
UserModel = get_user_model()
try:
return UserModel._default_manager.get(pk=user_id)
except UserModel.DoesNotExist:
return None
3、ModelBackend是如何實例化的
#1get_backends的方法的執行
def get_backends():
return _get_backends(return_tuples=False)
#2_get_backends的執行
def _get_backends(return_tuples=False):
backends = []
#2-1 獲取配置文件中的AUTHENTICATION_BACKENDS，是djanjo配置文件中的
#<type 'tuple'>: ('django.contrib.auth.backends.ModelBackend',)
for backend_path in settings.AUTHENTICATION_BACKENDS:
backend = load_backend(backend_path)
backends.append((backend, backend_path) if return_tuples else backend)
if not backends:
raise ImproperlyConfigured(
'No authentication backends have been defined. Does '
'AUTHENTICATION_BACKENDS contain anything?'
)
return backends
#2-2 load_backend方法的執行
def load_backend(path):
return import_string(path)()
#2-3 import_string 方法的執行 dotted_path：django.contrib.auth.backends.ModelBackend
def import_string(dotted_path):
"""
Import a dotted module path and return the attribute/class designated by the
last name in the path. Raise ImportError if the import failed.
"""
try:
module_path, class_name = dotted_path.rsplit('.', 1) #2-4 路徑分解module_path django.contrib.auth.backends
except ValueError:
msg = "%s doesn't look like a module path" % dotted_path
six.reraise(ImportError, ImportError(msg), sys.exc_info()[2])
module = import_module(module_path) # 2-5 映射文件中內容module_path django.contrib.auth.backends
try:
return getattr(module, class_name) #2-6 找到對應的ModelBackend類
except AttributeError:
msg = 'Module "%s" does not define a "%s" attribute/class' % (
dotted_path, class_name)
six.reraise(ImportError, ImportError(msg), sys.exc_info()[2])
4、settings.AUTHENTICATION_BACKENDS獲取詳解
#1、查看配置文件
class BaseSettings(object):
"""
Common logic for settings whether set by a module or by the user.
"""
def __setattr__(self, name, value):
if name in ("MEDIA_URL", "STATIC_URL") and value and not value.endswith('/'):
raise ImproperlyConfigured("If set, %s must end with a slash" % name)
object.__setattr__(self, name, value)
class Settings(BaseSettings):
def __init__(self, settings_module):
# update this dict from global settings (but only for ALL_CAPS settings)
for setting in dir(global_settings):
if setting.isupper():
setattr(self, setting, getattr(global_settings, setting))
# store the settings module in case someone later cares
self.SETTINGS_MODULE = settings_module
mod = importlib.import_module(self.SETTINGS_MODULE)
tuple_settings = (
"ALLOWED_INCLUDE_ROOTS",
"INSTALLED_APPS",
"TEMPLATE_DIRS",
"LOCALE_PATHS",
)
self._explicit_settings = set()
for setting in dir(mod):
if setting.isupper():
setting_value = getattr(mod, setting)
if (setting in tuple_settings and
isinstance(setting_value, six.string_types)):
raise ImproperlyConfigured("The %s setting must be a tuple. "
"Please fix your settings." % setting)
setattr(self, setting, setting_value)
self._explicit_settings.add(setting)
if not self.SECRET_KEY:
raise ImproperlyConfigured("The SECRET_KEY setting must not be empty.")
if ('django.contrib.auth.middleware.AuthenticationMiddleware' in self.MIDDLEWARE_CLASSES and
'django.contrib.auth.middleware.SessionAuthenticationMiddleware' not in self.MIDDLEWARE_CLASSES):
warnings.warn(
"Session verification will become mandatory in Django 2.0. "
"Please add 'django.contrib.auth.middleware.SessionAuthenticationMiddleware' "
"to your MIDDLEWARE_CLASSES setting when you are ready to opt-in after "
"reading the upgrade considerations in the 1.8 release notes.",
RemovedInDjango20Warning
)
if hasattr(time, 'tzset') and self.TIME_ZONE:
# When we can, attempt to validate the timezone. If we can't find
# this file, no check happens and it's harmless.
zoneinfo_root = '/usr/share/zoneinfo'
if (os.path.exists(zoneinfo_root) and not
os.path.exists(os.path.join(zoneinfo_root, *(self.TIME_ZONE.split('/'))))):
raise ValueError("Incorrect timezone setting: %s" % self.TIME_ZONE)
# Move the time zone info into os.environ. See ticket #2315 for why
# we don't do this unconditionally (breaks Windows).
os.environ['TZ'] = self.TIME_ZONE
time.tzset()
def is_overridden(self, setting):
return setting in self._explicit_settings
class LazySettings(LazyObject):
"""
A lazy proxy for either global Django settings or a custom settings object.
The user can manually configure settings prior to using them. Otherwise,
Django uses the settings module pointed to by DJANGO_SETTINGS_MODULE.
"""
def _setup(self, name=None):
"""
Load the settings module pointed to by the environment variable. This
is used the first time we need any settings at all, if the user has not
previously configured the settings manually.
"""
settings_module = os.environ.get(ENVIRONMENT_VARIABLE)
if not settings_module:
desc = ("setting %s" % name) if name else "settings"
raise ImproperlyConfigured(
"Requested %s, but settings are not configured. "
"You must either define the environment variable %s "
"or call settings.configure() before accessing settings."
% (desc, ENVIRONMENT_VARIABLE))
self._wrapped = Settings(settings_module)
def __getattr__(self, name):
if self._wrapped is empty:
self._setup(name)
return getattr(self._wrapped, name)
def configure(self, default_settings=global_settings, **options):
"""
Called to manually configure the settings. The 'default_settings'
parameter sets where to retrieve any unspecified values from (its
argument must support attribute access (__getattr__)).
"""
if self._wrapped is not empty:
raise RuntimeError('Settings already configured.')
holder = UserSettingsHolder(default_settings)
for name, value in options.items():
setattr(holder, name, value)
self._wrapped = holder
@property
def configured(self):
"""
Returns True if the settings have already been configured.
"""
return self._wrapped is not empty
settings = LazySettings()
#1、LazySettings實例化的時候同時也實例化了Settings
#1、settings實例化的時候將global_settings寫到了實例化的對象中
------------恢復內容開始------------
一可以借鑒的地方
1、單例模式
配置文件的引入：減少了開辟空間，其他好處想到了再補充
2、用戶組或用戶權限獲取時調用了一個方法（簡單工廠方法模式）
調用的防范並沒有使用if判斷而是使用了反射，擴展性較好
3、利用文件夾中init文件
二、源碼研究
1、找到項目中的代碼及進入方法內部
user = request.user
if user.has_perm('check')
2、源碼的執行的主流程
1、裝飾器的執行
def new_method_proxy(func):
def inner(self, *args):
if self._wrapped is empty: #user中的_wrapped一般不為empty
self._setup()
return func(self._wrapped, *args)
return inner
class PermissionsMixin(models.Model):
"""
A mixin class that adds the fields and methods necessary to support
Django's Group and Permission model using the ModelBackend.
"""
is_superuser = models.BooleanField(_('superuser status'), default=False,
help_text=_('Designates that this user has all permissions without '
'explicitly assigning them.'))
groups = models.ManyToManyField(Group, verbose_name=_('groups'),
blank=True, help_text=_('The groups this user belongs to. A user will '
'get all permissions granted to each of '
'their groups.'),
related_name="user_set", related_query_name="user")
user_permissions = models.ManyToManyField(Permission,
verbose_name=_('user permissions'), blank=True,
help_text=_('Specific permissions for this user.'),
related_name="user_set", related_query_name="user")
class Meta:
abstract = True
def get_group_permissions(self, obj=None):
"""
Returns a list of permission strings that this user has through their
groups. This method queries all available auth backends. If an object
is passed in, only permissions matching this object are returned.
"""
permissions = set()
for backend in auth.get_backends():
if hasattr(backend, "get_group_permissions"):
permissions.update(backend.get_group_permissions(self, obj))
return permissions
def get_all_permissions(self, obj=None):
return _user_get_all_permissions(self, obj)
2、執行has_perm self：user perm: 'check'
def has_perm(self, perm, obj=None):
"""
Returns True if the user has the specified permission. This method
queries all available auth backends, but returns immediately if any
backend returns True. Thus, a user who has permission from a single
auth backend is assumed to have permission in general. If an object is
provided, permissions for this specific object are checked.
"""
# Active superusers have all permissions.
if self.is_active and self.is_superuser:
return True
# Otherwise we need to check the backends.
return _user_has_perm(self, perm, obj)
def has_perms(self, perm_list, obj=None):
"""
Returns True if the user has each of the specified permissions. If
object is passed, it checks if the user has all required perms for this
object.
"""
for perm in perm_list:
if not self.has_perm(perm, obj):
return False
return True
def has_module_perms(self, app_label):
"""
Returns True if the user has any permissions in the given app label.
Uses pretty much the same logic as has_perm, above.
"""
# Active superusers have all permissions.
if self.is_active and self.is_superuser:
return True
return _user_has_module_perms(self, app_label)
3、執行 self：user perm: 'financial_flow.flow_financial' obj=None
def _user_has_perm(user, perm, obj):
"""
A backend can raise `PermissionDenied` to short-circuit permission checking.
"""
# shi3-1:實例化 backend
for backend in auth.get_backends():
if not hasattr(backend, 'has_perm'):
continue
try:
if backend.has_perm(user, perm, obj):
return True
except PermissionDenied:
return False
return False
4、backend 類中has_perm方法的執行
class ModelBackend(object):
"""
Authenticates against settings.AUTH_USER_MODEL.
"""
def authenticate(self, username=None, password=None, **kwargs):
UserModel = get_user_model()
if username is None:
username = kwargs.get(UserModel.USERNAME_FIELD)
try:
user = UserModel._default_manager.get_by_natural_key(username)
if user.check_password(password):
return user
except UserModel.DoesNotExist:
# Run the default password hasher once to reduce the timing
# difference between an existing and a non-existing user (#20760).
UserModel().set_password(password)
#4-2-4 獲取用戶的特殊權限
def _get_user_permissions(self, user_obj):
return user_obj.user_permissions.all()
#4-3-4獲取用戶組特殊權限
def _get_group_permissions(self, user_obj):
user_groups_field = get_user_model()._meta.get_field('groups')
user_groups_query = 'group__%s' % user_groups_field.related_query_name()
return Permission.objects.filter(**{user_groups_query: user_obj})
#4-2-2 獲取用戶的特殊權限
#4-3-2獲取用戶組特殊權限
def _get_permissions(self, user_obj, obj, from_name): #from_name user
"""
Returns the permissions of `user_obj` from `from_name`. `from_name` can
be either "group" or "user" to return permissions from
`_get_group_permissions` or `_get_user_permissions` respectively.
"""
if not user_obj.is_active or user_obj.is_anonymous() or obj is not None:
return set()
perm_cache_name = '_%s_perm_cache' % from_name #u'_user_perm_cache'
if not hasattr(user_obj, perm_cache_name):
if user_obj.is_superuser:
perms = Permission.objects.all()
else:
#4-2-3 獲取用戶的特殊權限
#4-3-3獲取用戶組特殊權限
perms = getattr(self, '_get_%s_permissions' % from_name)(user_obj) #_get_user_permissions
perms = perms.values_list('content_type__app_label', 'codename').order_by()
setattr(user_obj, perm_cache_name, set("%s.%s" % (ct, name) for ct, name in perms))
return getattr(user_obj, perm_cache_name)
#4-2-1獲取用戶的特殊權限
def get_user_permissions(self, user_obj, obj=None):
"""
Returns a set of permission strings the user `user_obj` has from their
`user_permissions`.
"""
return self._get_permissions(user_obj, obj, 'user')
#4-3-1獲取用戶組特殊權限
def get_group_permissions(self, user_obj, obj=None):
"""
Returns a set of permission strings the user `user_obj` has from the
groups they belong.
"""
return self._get_permissions(user_obj, obj, 'group')
#4-1獲取所有的權限
def get_all_permissions(self, user_obj, obj=None):
if not user_obj.is_active or user_obj.is_anonymous() or obj is not None:
return set()
if not hasattr(user_obj, '_perm_cache'):
#4-2 獲取用戶的特殊權限
user_obj._perm_cache = self.get_user_permissions(user_obj)
#4-3 獲取用戶所屬組的特殊群限
user_obj._perm_cache.update(self.get_group_permissions(user_obj))
return user_obj._perm_cache
def has_perm(self, user_obj, perm, obj=None):
if not user_obj.is_active:
return False
#4-1獲取所有的權限
return perm in self.get_all_permissions(user_obj, obj) #結果就是True或False
def has_module_perms(self, user_obj, app_label):
"""
Returns True if user_obj has any permissions in the given app_label.
"""
if not user_obj.is_active:
return False
for perm in self.get_all_permissions(user_obj):
if perm[:perm.index('.')] == app_label:
return True
return False
def get_user(self, user_id):
UserModel = get_user_model()
try:
return UserModel._default_manager.get(pk=user_id)
except UserModel.DoesNotExist:
return None
3、ModelBackend是如何實例化的
#1get_backends的方法的執行
def get_backends():
return _get_backends(return_tuples=False)
#2_get_backends的執行
def _get_backends(return_tuples=False):
backends = []
#2-1 獲取配置文件中的AUTHENTICATION_BACKENDS，是djanjo配置文件中的
#<type 'tuple'>: ('django.contrib.auth.backends.ModelBackend',)
for backend_path in settings.AUTHENTICATION_BACKENDS:
backend = load_backend(backend_path)
backends.append((backend, backend_path) if return_tuples else backend)
if not backends:
raise ImproperlyConfigured(
'No authentication backends have been defined. Does '
'AUTHENTICATION_BACKENDS contain anything?'
)
return backends
#2-2 load_backend方法的執行
def load_backend(path):
return import_string(path)()
#2-3 import_string 方法的執行 dotted_path：django.contrib.auth.backends.ModelBackend
def import_string(dotted_path):
"""
Import a dotted module path and return the attribute/class designated by the
last name in the path. Raise ImportError if the import failed.
"""
try:
module_path, class_name = dotted_path.rsplit('.', 1) #2-4 路徑分解module_path django.contrib.auth.backends
except ValueError:
msg = "%s doesn't look like a module path" % dotted_path
six.reraise(ImportError, ImportError(msg), sys.exc_info()[2])
module = import_module(module_path) # 2-5 映射文件中內容module_path django.contrib.auth.backends
try:
return getattr(module, class_name) #2-6 找到對應的ModelBackend類
except AttributeError:
msg = 'Module "%s" does not define a "%s" attribute/class' % (
dotted_path, class_name)
six.reraise(ImportError, ImportError(msg), sys.exc_info()[2])
4、settings.AUTHENTICATION_BACKENDS獲取詳解
#1、查看配置文件
class BaseSettings(object):
"""
Common logic for settings whether set by a module or by the user.
"""
def __setattr__(self, name, value):
if name in ("MEDIA_URL", "STATIC_URL") and value and not value.endswith('/'):
raise ImproperlyConfigured("If set, %s must end with a slash" % name)
object.__setattr__(self, name, value)
class Settings(BaseSettings):
def __init__(self, settings_module):
# update this dict from global settings (but only for ALL_CAPS settings)
for setting in dir(global_settings):
if setting.isupper():
setattr(self, setting, getattr(global_settings, setting))
# store the settings module in case someone later cares
self.SETTINGS_MODULE = settings_module
mod = importlib.import_module(self.SETTINGS_MODULE)
tuple_settings = (
"ALLOWED_INCLUDE_ROOTS",
"INSTALLED_APPS",
"TEMPLATE_DIRS",
"LOCALE_PATHS",
)
self._explicit_settings = set()
for setting in dir(mod):
if setting.isupper():
setting_value = getattr(mod, setting)
if (setting in tuple_settings and
isinstance(setting_value, six.string_types)):
raise ImproperlyConfigured("The %s setting must be a tuple. "
"Please fix your settings." % setting)
setattr(self, setting, setting_value)
self._explicit_settings.add(setting)
if not self.SECRET_KEY:
raise ImproperlyConfigured("The SECRET_KEY setting must not be empty.")
if ('django.contrib.auth.middleware.AuthenticationMiddleware' in self.MIDDLEWARE_CLASSES and
'django.contrib.auth.middleware.SessionAuthenticationMiddleware' not in self.MIDDLEWARE_CLASSES):
warnings.warn(
"Session verification will become mandatory in Django 2.0. "
"Please add 'django.contrib.auth.middleware.SessionAuthenticationMiddleware' "
"to your MIDDLEWARE_CLASSES setting when you are ready to opt-in after "
"reading the upgrade considerations in the 1.8 release notes.",
RemovedInDjango20Warning
)
if hasattr(time, 'tzset') and self.TIME_ZONE:
# When we can, attempt to validate the timezone. If we can't find
# this file, no check happens and it's harmless.
zoneinfo_root = '/usr/share/zoneinfo'
if (os.path.exists(zoneinfo_root) and not
os.path.exists(os.path.join(zoneinfo_root, *(self.TIME_ZONE.split('/'))))):
raise ValueError("Incorrect timezone setting: %s" % self.TIME_ZONE)
# Move the time zone info into os.environ. See ticket #2315 for why
# we don't do this unconditionally (breaks Windows).
os.environ['TZ'] = self.TIME_ZONE
time.tzset()
def is_overridden(self, setting):
return setting in self._explicit_settings
class LazySettings(LazyObject):
"""
A lazy proxy for either global Django settings or a custom settings object.
The user can manually configure settings prior to using them. Otherwise,
Django uses the settings module pointed to by DJANGO_SETTINGS_MODULE.
"""
def _setup(self, name=None):
"""
Load the settings module pointed to by the environment variable. This
is used the first time we need any settings at all, if the user has not
previously configured the settings manually.
"""
settings_module = os.environ.get(ENVIRONMENT_VARIABLE)
if not settings_module:
desc = ("setting %s" % name) if name else "settings"
raise ImproperlyConfigured(
"Requested %s, but settings are not configured. "
"You must either define the environment variable %s "
"or call settings.configure() before accessing settings."
% (desc, ENVIRONMENT_VARIABLE))
self._wrapped = Settings(settings_module)
def __getattr__(self, name):
if self._wrapped is empty:
self._setup(name)
return getattr(self._wrapped, name)
def configure(self, default_settings=global_settings, **options):
"""
Called to manually configure the settings. The 'default_settings'
parameter sets where to retrieve any unspecified values from (its
argument must support attribute access (__getattr__)).
"""
if self._wrapped is not empty:
raise RuntimeError('Settings already configured.')
holder = UserSettingsHolder(default_settings)
for name, value in options.items():
setattr(holder, name, value)
self._wrapped = holder
@property
def configured(self):
"""
Returns True if the settings have already been configured.
"""
return self._wrapped is not empty
settings = LazySettings()
#1、LazySettings實例化的時候同時也實例化了Settings
#1、settings實例化的時候將global_settings寫到了實例化的對象中
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