From 44a722042a4e321c38ac50b0b796a4fa494f09e4 Mon Sep 17 00:00:00 2001
From: Steven Armstrong <steven@icarus.ethz.ch>
Date: Mon, 10 Oct 2011 14:37:33 +0200
Subject: [PATCH] new class for using filesystem as backend for boolean
 properties

Signed-off-by: Steven Armstrong <steven@icarus.ethz.ch>
---
 lib/cdist/core/property.py | 47 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/lib/cdist/core/property.py b/lib/cdist/core/property.py
index e63cadcf..11dddcf3 100644
--- a/lib/cdist/core/property.py
+++ b/lib/cdist/core/property.py
@@ -165,3 +165,50 @@ class DirectoryDictProperty(DirectoryDict):
 
     def __delete__(self, obj):
         raise AttributeError("can't delete attribute")
+
+
+class FileBooleanProperty(object):
+    def __init__(self, path):
+        """
+        :param path: string or callable
+
+        Usage:
+
+        class Foo(object):
+            changed = FileBoolean(lambda obj: os.path.join(obj.absolute_path, 'changed'))
+            other_boolean = FileBoolean('/tmp/other_boolean')
+
+            def __init__(self):
+                self.absolute_path = '/tmp/foo_boolean'
+
+        """
+        self._path = path
+
+    def _get_path(self, *args, **kwargs):
+        path = self._path
+        if callable(path):
+            return path(*args, **kwargs)
+        if not os.path.isabs(path):
+            raise AbsolutePathRequiredError(path)
+        return path
+
+    # Descriptor Protocol
+    def __get__(self, obj, objtype=None):
+        if obj is None:
+            return self.__class__
+        path = self._get_path(obj)
+        return os.path.isfile(path)
+
+    def __set__(self, obj, value):
+        path = self._get_path(obj)
+        if value:
+            open(path, "w").close()
+        else:
+            try:
+                os.remove(path)
+            except EnvironmentError:
+                # ignore
+                pass
+
+    def __delete__(self, obj):
+        raise AttributeError("can't delete attribute")