added g_octave/installed.py, to help with the storage of packages

currently installed

1 files changed, 52 insertions, 0 deletions

diff --git a/g_octave/installed.py b/g_octave/installed.py
new file mode 100644
index 0000000..e749178
--- /dev/null
+++ b/g_octave/installed.py
@@ -0,0 +1,52 @@
+# -*- coding: utf-8 -*-
+
+"""
+    installed.py
+    ~~~~~~~~~~~~
+
+    This module implements a Python object with the register of g-octave
+    installed packages, something like the portage's world file.
+
+    :copyright: (c) 2010 by Rafael Goncalves Martins
+    :license: GPL-2, see LICENSE for more details.
+"""
+
+import json
+
+class Installed(object):
+    
+    # this will not be changed by the config file, because the user will
+    # lost track of the installed packages if he touch in the location
+    # of this file without move it.
+    _file = '/var/cache/g-octave.json'
+    
+    def _load_json(self):
+        content = {}
+        try:
+            with open(self._file) as fp:
+                content = json.load(fp)
+        except:
+            return {}
+        return content
+    
+    def _dump_json(self, content):
+        try:
+            with open(self._file, 'w') as fp:
+                json.dump(content, fp)
+        except:
+            return False
+        return True
+            
+    def do_install(self, package, version):
+        packages = self._load_json()
+        packages[package] = version
+        if not self._dump_json(packages):
+            raise RuntimeError('Failed to save JSON file.')
+    
+    def is_installed(self, package):
+        packages = self._load_json()
+        return package in packages
+    
+    def get_version(self, package):
+        packages = self._load_json()
+        return packages.get(package, None)