5c9c54bc09
Fix typos detected by toolkit misspellings. * pip install misspellings * git ls-files | grep -v locale | misspellings -f - Change-Id: I3d7c06bcc3b5d0cdf82b8da98a7fba15e935cab6
84 lines
2.5 KiB
Python
84 lines
2.5 KiB
Python
import sys
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import pkg_resources
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import inspect
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import logging
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log = logging.getLogger(__name__)
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class PecanExtensionMissing(ImportError):
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pass
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class PecanExtensionImporter(object):
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"""
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Short circuits imports for extensions.
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This is used in combination with ``pecan.ext`` so that when a user does
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``from pecan.ext import foo``, it will attempt to map ``foo`` to a
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registered setuptools entry point in some other (Pecan extension) project.
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Conversely, an extension developer may define an entry point in his
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``setup.py``, e.g.,
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setup(
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...
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entry_points='''
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[pecan.extension]
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celery = pecancelery.lib.core
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'''
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)
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This is mostly for convenience and consistency. In this way, Pecan can
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maintain an ecosystem of extensions that share a common namespace,
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``pecan.ext``, while still maintaining backwards compatibility for simple
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package names (e.g., ``pecancelery``).
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"""
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extension_module = 'pecan.ext'
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prefix = extension_module + '.'
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def install(self):
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if self not in sys.meta_path:
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sys.meta_path.append(self)
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def __eq__(self, b):
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return self.__class__.__module__ == b.__class__.__module__ and \
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self.__class__.__name__ == b.__class__.__name__
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def __ne__(self, b):
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return not self.__eq__(b)
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def find_module(self, fullname, path=None):
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if fullname.startswith(self.prefix):
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return self
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def load_module(self, fullname):
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if fullname in sys.modules:
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return self
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extname = fullname.split(self.prefix)[1]
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module = self.find_module_for_extension(extname)
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realname = module.__name__
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try:
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__import__(realname)
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except ImportError:
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raise sys.exc_info()
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module = sys.modules[fullname] = sys.modules[realname]
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if '.' not in extname:
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setattr(sys.modules[self.extension_module], extname, module)
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return module
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def find_module_for_extension(self, name):
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for ep in pkg_resources.iter_entry_points('pecan.extension'):
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if ep.name != name:
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continue
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log.debug('%s loading extension %s', self.__class__.__name__, ep)
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module = ep.load()
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if not inspect.ismodule(module):
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log.debug('%s is not a module, skipping...' % module)
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continue
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return module
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raise PecanExtensionMissing(
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'The `pecan.ext.%s` extension is not installed.' % name
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)
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