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# -*- test-case-name: twisted.test.test_sob -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
#
"""
Save and load Small OBjects to and from files, using various formats.
Maintainer: Moshe Zadka
"""
import os
import pickle
import sys
from zope.interface import Interface, implementer
from twisted.persisted import styles
from twisted.python import log, runtime
class IPersistable(Interface):
"""An object which can be saved in several formats to a file"""
def setStyle(style):
"""Set desired format.
@type style: string (one of 'pickle' or 'source')
"""
def save(tag=None, filename=None, passphrase=None):
"""Save object to file.
@type tag: string
@type filename: string
@type passphrase: string
"""
@implementer(IPersistable)
class Persistent:
style = "pickle"
def __init__(self, original, name):
self.original = original
self.name = name
def setStyle(self, style):
"""Set desired format.
@type style: string (one of 'pickle' or 'source')
"""
self.style = style
def _getFilename(self, filename, ext, tag):
if filename:
finalname = filename
filename = finalname + "-2"
elif tag:
filename = f"{self.name}-{tag}-2.{ext}"
finalname = f"{self.name}-{tag}.{ext}"
else:
filename = f"{self.name}-2.{ext}"
finalname = f"{self.name}.{ext}"
return finalname, filename
def _saveTemp(self, filename, dumpFunc):
with open(filename, "wb") as f:
dumpFunc(self.original, f)
def _getStyle(self):
if self.style == "source":
from twisted.persisted.aot import jellyToSource as dumpFunc
ext = "tas"
else:
def dumpFunc(obj, file=None):
pickle.dump(obj, file, 2)
ext = "tap"
return ext, dumpFunc
def save(self, tag=None, filename=None, passphrase=None):
"""Save object to file.
@type tag: string
@type filename: string
@type passphrase: string
"""
ext, dumpFunc = self._getStyle()
if passphrase is not None:
raise TypeError("passphrase must be None")
finalname, filename = self._getFilename(filename, ext, tag)
log.msg("Saving " + self.name + " application to " + finalname + "...")
self._saveTemp(filename, dumpFunc)
if runtime.platformType == "win32" and os.path.isfile(finalname):
os.remove(finalname)
os.rename(filename, finalname)
log.msg("Saved.")
# "Persistant" has been present since 1.0.7, so retain it for compatibility
Persistant = Persistent
class _EverythingEphemeral(styles.Ephemeral):
initRun = 0
def __init__(self, mainMod):
"""
@param mainMod: The '__main__' module that this class will proxy.
"""
self.mainMod = mainMod
def __getattr__(self, key):
try:
return getattr(self.mainMod, key)
except AttributeError:
if self.initRun:
raise
else:
log.msg("Warning! Loading from __main__: %s" % key)
return styles.Ephemeral()
def load(filename, style):
"""Load an object from a file.
Deserialize an object from a file. The file can be encrypted.
@param filename: string
@param style: string (one of 'pickle' or 'source')
"""
mode = "r"
if style == "source":
from twisted.persisted.aot import unjellyFromSource as _load
else:
_load, mode = pickle.load, "rb"
fp = open(filename, mode)
ee = _EverythingEphemeral(sys.modules["__main__"])
sys.modules["__main__"] = ee
ee.initRun = 1
with fp:
try:
value = _load(fp)
finally:
# restore __main__ if an exception is raised.
sys.modules["__main__"] = ee.mainMod
styles.doUpgrade()
ee.initRun = 0
persistable = IPersistable(value, None)
if persistable is not None:
persistable.setStyle(style)
return value
def loadValueFromFile(filename, variable):
"""Load the value of a variable in a Python file.
Run the contents of the file in a namespace and return the result of the
variable named C{variable}.
@param filename: string
@param variable: string
"""
with open(filename) as fileObj:
data = fileObj.read()
d = {"__file__": filename}
codeObj = compile(data, filename, "exec")
eval(codeObj, d, d)
value = d[variable]
return value
def guessType(filename):
ext = os.path.splitext(filename)[1]
return {
".tac": "python",
".etac": "python",
".py": "python",
".tap": "pickle",
".etap": "pickle",
".tas": "source",
".etas": "source",
}[ext]
__all__ = [
"loadValueFromFile",
"load",
"Persistent",
"Persistant",
"IPersistable",
"guessType",
]
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