Files
deb-python-django-compressor/compressor/utils.py
2011-03-30 12:10:39 +02:00

271 lines
8.5 KiB
Python

import os
import sys
from inspect import getmembers
from shlex import split as cmd_split
from django.conf import settings
from compressor.exceptions import FilterError
try:
any
except NameError:
def any(seq):
for item in seq:
if item:
return True
return False
def get_class(class_string, exception=FilterError):
"""
Convert a string version of a function name to the callable object.
"""
if not hasattr(class_string, '__bases__'):
try:
class_string = class_string.encode('ascii')
mod_name, class_name = get_mod_func(class_string)
if class_name != '':
cls = getattr(__import__(mod_name, {}, {}, ['']), class_name)
except (ImportError, AttributeError):
pass
else:
return cls
raise exception('Failed to import %s' % class_string)
def get_mod_func(callback):
"""
Converts 'django.views.news.stories.story_detail' to
('django.views.news.stories', 'story_detail')
"""
try:
dot = callback.rindex('.')
except ValueError:
return callback, ''
return callback[:dot], callback[dot + 1:]
def walk(root, topdown=True, onerror=None, followlinks=False):
"""
A version of os.walk that can follow symlinks for Python < 2.6
"""
for dirpath, dirnames, filenames in os.walk(root, topdown, onerror):
yield (dirpath, dirnames, filenames)
if followlinks:
for d in dirnames:
p = os.path.join(dirpath, d)
if os.path.islink(p):
for link_dirpath, link_dirnames, link_filenames in walk(p):
yield (link_dirpath, link_dirnames, link_filenames)
# Taken from Django 1.3 and before that from Python 2.7
# with permission from the original author.
def _resolve_name(name, package, level):
"""Return the absolute name of the module to be imported."""
if not hasattr(package, 'rindex'):
raise ValueError("'package' not set to a string")
dot = len(package)
for x in xrange(level, 1, -1):
try:
dot = package.rindex('.', 0, dot)
except ValueError:
raise ValueError("attempted relative import beyond top-level "
"package")
return "%s.%s" % (package[:dot], name)
def import_module(name, package=None):
"""Import a module.
The 'package' argument is required when performing a relative import. It
specifies the package to use as the anchor point from which to resolve the
relative import to an absolute import.
"""
if name.startswith('.'):
if not package:
raise TypeError("relative imports require the 'package' argument")
level = 0
for character in name:
if character != '.':
break
level += 1
name = _resolve_name(name[level:], package, level)
__import__(name)
return sys.modules[name]
class AppSettings(object):
"""
An app setting object to be used for handling app setting defaults
gracefully and providing a nice API for them. Say you have an app
called ``myapp`` and want to define a few defaults, and refer to the
defaults easily in the apps code. Add a ``settings.py`` to your app::
from path.to.utils import AppSettings
class MyAppSettings(AppSettings):
SETTING_1 = "one"
SETTING_2 = (
"two",
)
Then initialize the setting with the correct prefix in the location of
of your choice, e.g. ``conf.py`` of the app module::
settings = MyAppSettings(prefix="MYAPP")
The ``MyAppSettings`` instance will automatically look at Django's
global setting to determine each of the settings and respect the
provided ``prefix``. E.g. adding this to your site's ``settings.py``
will set the ``SETTING_1`` setting accordingly::
MYAPP_SETTING_1 = "uno"
Usage
-----
Instead of using ``from django.conf import settings`` as you would
usually do, you can switch to using your apps own settings module
to access the app settings::
from myapp.conf import settings
print myapp_settings.MYAPP_SETTING_1
``AppSettings`` instances also work as pass-throughs for other
global settings that aren't related to the app. For example the
following code is perfectly valid::
from myapp.conf import settings
if "myapp" in settings.INSTALLED_APPS:
print "yay, myapp is installed!"
Custom handling
---------------
Each of the settings can be individually configured with callbacks.
For example, in case a value of a setting depends on other settings
or other dependencies. The following example sets one setting to a
different value depending on a global setting::
from django.conf import settings
class MyCustomAppSettings(AppSettings):
ENABLED = True
def configure_enabled(self, value):
return value and not self.DEBUG
custom_settings = MyCustomAppSettings("MYAPP")
The value of ``custom_settings.MYAPP_ENABLED`` will vary depending on the
value of the global ``DEBUG`` setting.
Each of the app settings can be customized by providing
a method ``configure_<lower_setting_name>`` that takes the default
value as defined in the class attributes as the only parameter.
The method needs to return the value to be use for the setting in
question.
"""
def __dir__(self):
return sorted(list(set(self.__dict__.keys() + dir(settings))))
__members__ = lambda self: self.__dir__()
def __getattr__(self, name):
if name.startswith(self._prefix):
raise AttributeError("%r object has no attribute %r" %
(self.__class__.__name__, name))
return getattr(settings, name)
def __setattr__(self, name, value):
super(AppSettings, self).__setattr__(name, value)
if name in dir(settings):
setattr(settings, name, value)
def __init__(self, prefix):
super(AppSettings, self).__setattr__('_prefix', prefix)
for name, value in filter(self.issetting, getmembers(self.__class__)):
prefixed_name = "%s_%s" % (prefix.upper(), name.upper())
value = getattr(settings, prefixed_name, value)
callback = getattr(self, "configure_%s" % name.lower(), None)
if callable(callback):
value = callback(value)
delattr(self.__class__, name)
setattr(self, prefixed_name, value)
def issetting(self, (name, value)):
return name == name.upper()
class cached_property(object):
"""Property descriptor that caches the return value
of the get function.
*Examples*
.. code-block:: python
@cached_property
def connection(self):
return Connection()
@connection.setter # Prepares stored value
def connection(self, value):
if value is None:
raise TypeError("Connection must be a connection")
return value
@connection.deleter
def connection(self, value):
# Additional action to do at del(self.attr)
if value is not None:
print("Connection %r deleted" % (value, ))
"""
def __init__(self, fget=None, fset=None, fdel=None, doc=None):
self.__get = fget
self.__set = fset
self.__del = fdel
self.__doc__ = doc or fget.__doc__
self.__name__ = fget.__name__
self.__module__ = fget.__module__
def __get__(self, obj, type=None):
if obj is None:
return self
try:
return obj.__dict__[self.__name__]
except KeyError:
value = obj.__dict__[self.__name__] = self.__get(obj)
return value
def __set__(self, obj, value):
if obj is None:
return self
if self.__set is not None:
value = self.__set(obj, value)
obj.__dict__[self.__name__] = value
def __delete__(self, obj):
if obj is None:
return self
try:
value = obj.__dict__.pop(self.__name__)
except KeyError:
pass
else:
if self.__del is not None:
self.__del(obj, value)
def setter(self, fset):
return self.__class__(self.__get, fset, self.__del)
def deleter(self, fdel):
return self.__class__(self.__get, self.__set, fdel)