dosage/dosagelib/loader.py

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# -*- coding: iso-8859-1 -*-
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# Copyright (C) 2012 Bastian Kleineidam
"""
Functions to load plugin modules.
"""
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import os
import sys
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def get_modules(folder, importprefix):
"""Find all valid modules in the plugins directory. A valid module
must have a .py extension, and is importable.
@return: all loaded valid modules
@rtype: iterator of module
"""
for filename in get_importable_modules(folder):
try:
module = load_module(filename, importprefix)
if module is not None:
yield module
except StandardError, msg:
print "ERROR: could not load module %s: %s" % (filename, msg)
def get_importable_modules(folder):
"""Find all module files in the given folder that end witn '.py' and
don't start with an underscore.
@return module filenames
@rtype: iterator of string
"""
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for fname in sorted(os.listdir(folder)):
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if fname.endswith('.py') and not fname.startswith('_'):
yield os.path.join(folder, fname)
def load_module(filename, importprefix):
"""Load and return the module given by the filename.
Other exceptions than ImportError are not catched.
@return: loaded module or None on import errors
@rtype: module or None
"""
name = os.path.splitext(os.path.basename(filename))[0]
modulename = "%s%s" % (importprefix, name)
__import__(modulename)
return sys.modules[modulename]
def get_plugins(modules, classobj):
"""Find all scrapers in all modules.
@param modules: the modules to search
@ptype modules: iterator of modules
@return: found scrapers
@rytpe: iterator of class objects
"""
for module in modules:
for plugin in get_module_plugins(module, classobj):
yield plugin
def get_module_plugins(module, classobj):
"""Return all subclasses of _BasicScraper in the module.
If the module defines __all__, only those entries will be searched,
otherwise all objects not starting with '_' will be searched.
"""
try:
names = module.__all__
except AttributeError:
names = [x for x in vars(module) if not x.startswith('_')]
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for name in sorted(names):
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try:
obj = getattr(module, name)
except AttributeError:
continue
try:
if issubclass(obj, classobj):
yield obj
except TypeError:
continue