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Diffstat (limited to 'libbe/settings_object.py')
| -rw-r--r-- | libbe/settings_object.py | 353 |
1 files changed, 353 insertions, 0 deletions
diff --git a/libbe/settings_object.py b/libbe/settings_object.py new file mode 100644 index 0000000..1df3e6b --- /dev/null +++ b/libbe/settings_object.py @@ -0,0 +1,353 @@ +# Bugs Everywhere - a distributed bugtracker +# Copyright (C) 2008 W. Trevor King <wking@drexel.edu> +# +# This program is free software: you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation, either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see <http://www.gnu.org/licenses/>. + +""" +This module provides a base class implementing settings-dict based +property storage useful for BE objects with saved properties +(e.g. BugDir, Bug, Comment). For example usage, consider the +unittests at the end of the module. +""" + +import doctest +import unittest + +from properties import Property, doc_property, local_property, \ + defaulting_property, checked_property, fn_checked_property, \ + cached_property, primed_property, change_hook_property, \ + settings_property + + +class _Token (object): + """ + `Control' value class for properties. We want values that only + mean something to the settings_object module. + """ + pass + +class UNPRIMED (_Token): + "Property has not been primed." + pass + +class EMPTY (_Token): + """ + Property has been primed but has no user-set value, so use + default/generator value. + """ + pass + + +def prop_save_settings(self, old, new): + """ + The default action undertaken when a property changes. + """ + if self.sync_with_disk==True: + self.save_settings() + +def prop_load_settings(self): + """ + The default action undertaken when an UNPRIMED property is accessed. + """ + if self.sync_with_disk==True and self._settings_loaded==False: + self.load_settings() + else: + self._setup_saved_settings(flag_as_loaded=False) + +# Some name-mangling routines for pretty printing setting names +def setting_name_to_attr_name(self, name): + """ + Convert keys to the .settings dict into their associated + SavedSettingsObject attribute names. + >>> print setting_name_to_attr_name(None,"User-id") + user_id + """ + return name.lower().replace('-', '_') + +def attr_name_to_setting_name(self, name): + """ + The inverse of setting_name_to_attr_name. + >>> print attr_name_to_setting_name(None, "user_id") + User-id + """ + return name.capitalize().replace('_', '-') + + +def versioned_property(name, doc, + default=None, generator=None, + change_hook=prop_save_settings, + primer=prop_load_settings, + allowed=None, check_fn=None, + settings_properties=[], + required_saved_properties=[], + require_save=False): + """ + Combine the common decorators in a single function. + + Use zero or one (but not both) of default or generator, since a + working default will keep the generator from functioning. Use the + default if you know what you want the default value to be at + 'coding time'. Use the generator if you can write a function to + determine a valid default at run time. If both default and + generator are None, then the property will be a defaulting + property which defaults to None. + + allowed and check_fn have a similar relationship, although you can + use both of these if you want. allowed compares the proposed + value against a list determined at 'coding time' and check_fn + allows more flexible comparisons to take place at run time. + + Set require_save to True if you want to save the default/generated + value for a property, to protect against future changes. E.g., we + currently expect all comments to be 'text/plain' but in the future + we may want to default to 'text/html'. If we don't want the old + comments to be interpreted as 'text/html', we would require that + the content type be saved. + + change_hook, primer, settings_properties, and + required_saved_properties are only options to get their defaults + into our local scope. Don't mess with them. + """ + settings_properties.append(name) + if require_save == True: + required_saved_properties.append(name) + def decorator(funcs): + fulldoc = doc + if default != None: + defaulting = defaulting_property(default=default, null=EMPTY) + fulldoc += "\n\nThis property defaults to %s" % default + if generator != None: + cached = cached_property(generator=generator, initVal=EMPTY) + fulldoc += "\n\nThis property is generated with %s" % generator + if check_fn != None: + fn_checked = fn_checked_property(value_allowed_fn=check_fn) + fulldoc += "\n\nThis property is checked with %s" % check_fn + if allowed != None: + checked = checked_property(allowed=allowed) + fulldoc += "\n\nThe allowed values for this property are: %s." \ + % (', '.join(allowed)) + hooked = change_hook_property(hook=change_hook) + primed = primed_property(primer=primer, initVal=UNPRIMED) + settings = settings_property(name=name, null=UNPRIMED) + docp = doc_property(doc=fulldoc) + deco = hooked(primed(settings(docp(funcs)))) + if default != None: + deco = defaulting(deco) + if generator != None: + deco = cached(deco) + if default != None: + deco = defaulting(deco) + if allowed != None: + deco = checked(deco) + if check_fn != None: + deco = fn_checked(deco) + return Property(deco) + return decorator + +class SavedSettingsObject(object): + + # Keep a list of properties that may be stored in the .settings dict. + #settings_properties = [] + + # A list of properties that we save to disk, even if they were + # never set (in which case we save the default value). This + # protects against future changes in default values. + #required_saved_properties = [] + + _setting_name_to_attr_name = setting_name_to_attr_name + _attr_name_to_setting_name = attr_name_to_setting_name + + def __init__(self): + self._settings_loaded = False + self.sync_with_disk = False + self.settings = {} + + def load_settings(self): + """Load the settings from disk.""" + # Override. Must call ._setup_saved_settings() after loading. + self.settings = {} + self._setup_saved_settings() + + def _setup_saved_settings(self, flag_as_loaded=True): + """ + To be run after setting self.settings up from disk. Marks all + settings as primed. + """ + for property in self.settings_properties: + if property not in self.settings: + self.settings[property] = EMPTY + elif self.settings[property] == UNPRIMED: + self.settings[property] = EMPTY + if flag_as_loaded == True: + self._settings_loaded = True + + def save_settings(self): + """Load the settings from disk.""" + # Override. Should save the dict output of ._get_saved_settings() + settings = self._get_saved_settings() + pass # write settings to disk.... + + def _get_saved_settings(self): + settings = {} + for k,v in self.settings.items(): + if v != None and v != EMPTY: + settings[k] = v + for k in self.required_saved_properties: + settings[k] = getattr(self, self._setting_name_to_attr_name(k)) + return settings + + def clear_cached_setting(self, setting=None): + "If setting=None, clear *all* cached settings" + if setting != None: + if hasattr(self, "_%s_cached_value" % setting): + delattr(self, "_%s_cached_value" % setting) + else: + for setting in settings_properties: + self.clear_cached_setting(setting) + + +class SavedSettingsObjectTests(unittest.TestCase): + def testSimpleProperty(self): + class Test(SavedSettingsObject): + settings_properties = [] + required_saved_properties = [] + @versioned_property(name="Content-type", + doc="A test property", + settings_properties=settings_properties, + required_saved_properties=required_saved_properties) + def content_type(): return {} + def __init__(self): + SavedSettingsObject.__init__(self) + t = Test() + # access missing setting + self.failUnless(t._settings_loaded == False, t._settings_loaded) + self.failUnless(len(t.settings) == 0, len(t.settings)) + self.failUnless(t.content_type == EMPTY, t.content_type) + # accessing t.content_type triggers the priming, which runs + # t._setup_saved_settings, which fills out t.settings with + # EMPTY data. t._settings_loaded is still false though, since + # the default priming does not do any of the `official' loading + # that occurs in t.load_settings. + self.failUnless(len(t.settings) == 1, len(t.settings)) + self.failUnless(t.settings["Content-type"] == EMPTY, + t.settings["Content-type"]) + self.failUnless(t._settings_loaded == False, t._settings_loaded) + # load settings creates an EMPTY value in the settings array + t.load_settings() + self.failUnless(t._settings_loaded == True, t._settings_loaded) + self.failUnless(t.settings["Content-type"] == EMPTY, + t.settings["Content-type"]) + self.failUnless(t.content_type == EMPTY, t.content_type) + self.failUnless(len(t.settings) == 1, len(t.settings)) + self.failUnless(t.settings["Content-type"] == EMPTY, + t.settings["Content-type"]) + # now we set a value + t.content_type = None + self.failUnless(t.settings["Content-type"] == None, + t.settings["Content-type"]) + self.failUnless(t.content_type == None, t.content_type) + self.failUnless(t.settings["Content-type"] == None, + t.settings["Content-type"]) + # now we set another value + t.content_type = "text/plain" + self.failUnless(t.content_type == "text/plain", t.content_type) + self.failUnless(t.settings["Content-type"] == "text/plain", + t.settings["Content-type"]) + self.failUnless(t._get_saved_settings()=={"Content-type":"text/plain"}, + t._get_saved_settings()) + # now we clear to the post-primed value + t.content_type = EMPTY + self.failUnless(t._settings_loaded == True, t._settings_loaded) + self.failUnless(t.settings["Content-type"] == EMPTY, + t.settings["Content-type"]) + self.failUnless(t.content_type == EMPTY, t.content_type) + self.failUnless(len(t.settings) == 1, len(t.settings)) + self.failUnless(t.settings["Content-type"] == EMPTY, + t.settings["Content-type"]) + def testDefaultingProperty(self): + class Test(SavedSettingsObject): + settings_properties = [] + required_saved_properties = [] + @versioned_property(name="Content-type", + doc="A test property", + default="text/plain", + settings_properties=settings_properties, + required_saved_properties=required_saved_properties) + def content_type(): return {} + def __init__(self): + SavedSettingsObject.__init__(self) + t = Test() + self.failUnless(t._settings_loaded == False, t._settings_loaded) + self.failUnless(t.content_type == "text/plain", t.content_type) + self.failUnless(t._settings_loaded == False, t._settings_loaded) + t.load_settings() + self.failUnless(t._settings_loaded == True, t._settings_loaded) + self.failUnless(t.content_type == "text/plain", t.content_type) + self.failUnless(t.settings["Content-type"] == EMPTY, + t.settings["Content-type"]) + self.failUnless(t._get_saved_settings() == {}, t._get_saved_settings()) + t.content_type = "text/html" + self.failUnless(t.content_type == "text/html", + t.content_type) + self.failUnless(t.settings["Content-type"] == "text/html", + t.settings["Content-type"]) + self.failUnless(t._get_saved_settings()=={"Content-type":"text/html"}, + t._get_saved_settings()) + def testRequiredDefaultingProperty(self): + class Test(SavedSettingsObject): + settings_properties = [] + required_saved_properties = [] + @versioned_property(name="Content-type", + doc="A test property", + default="text/plain", + settings_properties=settings_properties, + required_saved_properties=required_saved_properties, + require_save=True) + def content_type(): return {} + def __init__(self): + SavedSettingsObject.__init__(self) + t = Test() + self.failUnless(t._get_saved_settings()=={"Content-type":"text/plain"}, + t._get_saved_settings()) + t.content_type = "text/html" + self.failUnless(t._get_saved_settings()=={"Content-type":"text/html"}, + t._get_saved_settings()) + def testClassVersionedPropertyDefinition(self): + class Test(SavedSettingsObject): + settings_properties = [] + required_saved_properties = [] + def _versioned_property(settings_properties=settings_properties, + required_saved_properties=required_saved_properties, + **kwargs): + if "settings_properties" not in kwargs: + kwargs["settings_properties"] = settings_properties + if "required_saved_properties" not in kwargs: + kwargs["required_saved_properties"]=required_saved_properties + return versioned_property(**kwargs) + @_versioned_property(name="Content-type", + doc="A test property", + default="text/plain", + require_save=True) + def content_type(): return {} + def __init__(self): + SavedSettingsObject.__init__(self) + t = Test() + self.failUnless(t._get_saved_settings()=={"Content-type":"text/plain"}, + t._get_saved_settings()) + t.content_type = "text/html" + self.failUnless(t._get_saved_settings()=={"Content-type":"text/html"}, + t._get_saved_settings()) + +unitsuite=unittest.TestLoader().loadTestsFromTestCase(SavedSettingsObjectTests) +suite = unittest.TestSuite([unitsuite, doctest.DocTestSuite()]) |