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"""Core object-file mapping functionality.""" |
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import functools |
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from pprint import pformat |
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from . import common, diskutils, exceptions, types, settings |
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from .bases import Container |
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log = common.logger(__name__) |
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def file_required(create=False): |
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"""Decorator for methods that require the file to exist. |
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:param create: boolean or the method to decorate |
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""" |
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def decorator(method): |
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@functools.wraps(method) |
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def wrapped(self, *args, **kwargs): |
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if not self.exists and self.auto: |
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if create is True and not self.deleted: |
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self.create() |
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else: |
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msg = "Cannot access deleted: {}".format(self.path) |
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raise exceptions.FileDeletedError(msg) |
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return method(self, *args, **kwargs) |
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return wrapped |
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if callable(create): |
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return decorator(create) |
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else: |
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return decorator |
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def prevent_recursion(method): |
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"""Decorator to prevent indirect recursive calls.""" |
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@functools.wraps(method) |
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def wrapped(self, *args, **kwargs): |
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# pylint: disable=protected-access |
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if self._activity: |
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return |
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self._activity = True |
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result = method(self, *args, **kwargs) |
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self._activity = False |
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return result |
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return wrapped |
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def prefix(obj): |
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"""Prefix a string with a fake designator if enabled.""" |
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fake = "(fake) " if settings.fake else "" |
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name = obj if isinstance(obj, str) else "'{}'".format(obj) |
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return fake + name |
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class Mapper: |
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"""Utility class to map an object's attributes to a file. |
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To start mapping attributes to a file: |
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create -> [empty] -> FILE |
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When getting an attribute: |
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FILE -> read -> [text] -> load -> [dict] -> fetch -> ATTRIBUTES |
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When setting an attribute: |
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ATTRIBUTES -> store -> [dict] -> dump -> [text] -> write -> FILE |
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After the mapped file is no longer needed: |
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delete -> [null] -> FILE |
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""" |
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def __init__(self, obj, path, attrs, *, auto=True, strict=True): |
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self._obj = obj |
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self.path = path |
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self.attrs = attrs |
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self.auto = auto |
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self.strict = strict |
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self.exists = diskutils.exists(self.path) |
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self.deleted = False |
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self.store_after_fetch = False |
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self._activity = False |
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self._timestamp = 0 |
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self._fake = "" |
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def __str__(self): |
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return str(self.path) |
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@property |
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def modified(self): |
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"""Determine if the file has been modified.""" |
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if settings.fake: |
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changes = self._timestamp is not None |
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return changes |
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elif not self.exists: |
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return True |
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else: |
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was = self._timestamp |
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now = diskutils.stamp(self.path) |
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return was != now |
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@modified.setter |
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@file_required(create=True) |
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def modified(self, changes): |
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"""Mark the file as modified if there are changes.""" |
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if changes: |
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log.debug("Marked %s as modified", prefix(self)) |
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self._timestamp = 0 |
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else: |
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if settings.fake or self.path is None: |
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self._timestamp = None |
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else: |
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self._timestamp = diskutils.stamp(self.path) |
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log.debug("Marked %s as unmodified", prefix(self)) |
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@property |
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def text(self): |
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"""Get file contents.""" |
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log.info("Getting contents of %s...", prefix(self)) |
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if settings.fake: |
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text = self._fake |
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else: |
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text = self._read() |
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log.trace("Text read: \n%s", text[:-1]) |
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return text |
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@text.setter |
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def text(self, text): |
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"""Set file contents.""" |
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log.info("Setting contents of %s...", prefix(self)) |
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if settings.fake: |
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self._fake = text |
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else: |
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self._write(text) |
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log.trace("Text wrote: \n%s", text.rstrip()) |
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self.modified = True |
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def create(self): |
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"""Create a new file for the object.""" |
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log.info("Creating %s for %r...", prefix(self), self._obj) |
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if self.exists: |
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log.warning("Already created: %s", self) |
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return |
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if not settings.fake: |
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diskutils.touch(self.path) |
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self.exists = True |
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self.deleted = False |
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@file_required |
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@prevent_recursion |
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def fetch(self): |
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"""Update the object's mapped attributes from its file.""" |
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log.info("Fetching %r from %s...", self._obj, prefix(self)) |
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# Parse data from file |
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text = self._read() |
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data = diskutils.load(text=text, path=self.path) |
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log.trace("Loaded data: \n%s", pformat(data)) |
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# Update all attributes |
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attrs2 = self.attrs.copy() |
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for name, data in data.items(): |
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attrs2.pop(name, None) |
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# Find a matching converter |
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try: |
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converter = self.attrs[name] |
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except KeyError: |
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if self.strict: |
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msg = "Ignored unknown file attribute: %s = %r" |
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log.warning(msg, name, data) |
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continue |
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else: |
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converter = types.match(name, data) |
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self.attrs[name] = converter |
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# Convert the loaded attribute |
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attr = getattr(self._obj, name, None) |
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if all((isinstance(attr, converter), |
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issubclass(converter, Container))): |
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attr.update_value(data, strict=self.strict) |
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else: |
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attr = converter.to_value(data) |
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setattr(self._obj, name, attr) |
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self._remap(attr, self) |
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log.trace("Value fetched: %s = %r", name, attr) |
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# Add missing attributes |
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for name, converter in attrs2.items(): |
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if not hasattr(self._obj, name): |
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value = converter.to_value(None) |
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msg = "Default value for missing object attribute: %s = %r" |
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log.warning(msg, name, value) |
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setattr(self._obj, name, value) |
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# Set meta attributes |
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self.modified = False |
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def _remap(self, obj, root): |
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"""Restore mapping on nested attributes.""" |
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if isinstance(obj, Container): |
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common.set_mapper(obj, root) |
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215
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if isinstance(obj, dict): |
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for obj2 in obj.values(): |
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self._remap(obj2, root) |
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else: |
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assert isinstance(obj, list) |
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for obj2 in obj: |
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self._remap(obj2, root) |
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223
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@file_required(create=True) |
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@prevent_recursion |
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def store(self): |
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"""Format and save the object's mapped attributes to its file.""" |
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log.info("Storing %r to %s...", self._obj, prefix(self)) |
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# Format the data items |
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data = self.attrs.__class__() |
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for name, converter in self.attrs.items(): |
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try: |
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value = getattr(self._obj, name) |
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except AttributeError: |
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data2 = converter.to_data(None) |
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msg = "Default data for missing object attribute: %s = %r" |
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log.warning(msg, name, data2) |
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else: |
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data2 = converter.to_data(value) |
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log.trace("Data to store: %s = %r", name, data2) |
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data[name] = data2 |
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# Dump data to file |
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text = diskutils.dump(data=data, path=self.path) |
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self._write(text) |
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# Set meta attributes |
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self.modified = True |
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self.store_after_fetch = self.auto |
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252
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def delete(self): |
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"""Delete the object's file from the file system.""" |
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if self.exists: |
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log.info("Deleting %s...", prefix(self)) |
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diskutils.delete(self.path) |
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else: |
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log.warning("Already deleted: %s", self) |
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self.exists = False |
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self.deleted = True |
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262
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@file_required |
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def _read(self): |
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"""Read text from the object's file.""" |
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if settings.fake: |
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return self._fake |
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267
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elif not self.exists: |
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return "" |
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else: |
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return diskutils.read(self.path) |
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@file_required |
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def _write(self, text): |
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"""Write text to the object's file.""" |
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if settings.fake: |
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self._fake = text |
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else: |
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diskutils.write(text, self.path) |
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jacebrowning /
yorm
