[cranslib/conffile] Une librairie pour gérer les fichiers de configuration

* S'utilise avec un context manager, le but est de faire un fichier
 temporaire de backup, et de s'assurer qu'on ferme bien le fichier dans
 lequel on écrit au fur et à mesure du temps

cranslib/conffile.py

@@ -0,0 +1,81 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+#
+# Library designed to write in config files data
+# safely.
+#
+# Author  : Pierre-Elliott Bécue <becue@crans.org>
+# License : GPLv3
+# Date    : 30/05/2014
+
+import tempfile
+import shutil
+import sys
+import time
+
+class ConfFile(object):
+    """Class handling ConfigFiles
+
+    """
+    def __init__(self, filename):
+        self._name = filename
+        self._backup = None
+        self._fd = None
+
+    def __enter__(self):
+        """This file is used in context manager
+
+        In case of syntax "with ConfFile("blop") as troll,
+        troll will bind on self
+
+        """
+        self.safe_open()
+        return self
+
+    def __exit__(self, etype, evalue, etraceback):
+        """Closes file, and, if there is any traceback, restores
+        the backup
+
+        """
+        self._fd.close()
+        if etype:
+            # In case of exception, cleans the mess.
+            self.restore()
+
+    def safe_open(self):
+        """Open a file in writemode but backups it before.
+
+        """
+        self._backup = tempfile.NamedTemporaryFile()
+        try:
+            shutil.copyfile(self._name, self._backup.name)
+        except IOError:
+            self._backup = None
+
+        self._fd = open(self._name, 'w')
+
+    def write(self, data):
+        """Writes data into file
+
+        """
+        self._fd.write(data)
+
+    def restore(self):
+        """Restores the tempfile
+
+        """
+        if self._backup is not None:
+            shutil.copyfile(self._backup.name, self._name)
+
+    def header(self, comment="#"):
+        myHeader = """********************************************************************************************
+ This file was generated automatically using the software %s.
+
+ You should not modify it directly if you don't know what you are doing.
+
+ Date : %s
+********************************************************************************************""" % (sys.argv[0].split("/")[-1], time.strftime("%d/%m/%Y - %H:%M:%S", time.localtime()))
+        myHeader = comment + myHeader.replace("\n", "\n%s" % (comment,))
+        myHeader += "\n\n"
+
+        self.write(myHeader)