Rewrote the database initialization to be a class instead of a function

5 files changed, 76 insertions, 50 deletions

diff --git a/portato/db/__init__.py b/portato/db/__init__.py
index 21f72ce..850a84e 100644
--- a/portato/db/__init__.py
+++ b/portato/db/__init__.py
@@ -12,66 +12,66 @@
 
 from __future__ import absolute_import
 
+from . import database as db
+from .exceptions import UnknownDatabaseTypeError, DatabaseInstantiationError
 from ..session import Session, SectionDict
 from ..helper import debug, warning, error
 
-class UnknownDatabaseTypeError (Exception):
-    pass
-
-_SESSION = None
-_TYPE = None
-_DEFAULT = "dict"
-_DATABASE = None
-
 types = {
         "sql": (_("SQLite"), _("Uses an SQLite-database to store package information.\nMay take longer to generate at the first time, but has advantages if portato is re-started with an unchanged portage tree. Additionally it allows to use fast SQL expressions for fetching the data.")),
         "dict": (_("Hashmap"), _("Uses an in-memory hashmap to store package information.\nHas been used since at least version 0.3.3, but all information has to be regenerated on each startup.")),
         "eixsql" : (_("eix + SQLite"), _("Similar to SQLite, but now uses the eix database to get the package information.\nThis should be much faster on startup, but requires that your eix database is always up-to-date.\nAdditionally, this is the only database allowing searching in descriptions."))
         }
 
-def Database(type = None):
-    global _SESSION, _TYPE, _DATABASE
+class Database(db.Database):
+    DEFAULT = "dict"
 
-    if type is None:
-        if _DATABASE is None:
-            warning("No database type specified! Falling back to default.")
-            return Database(_DEFAULT)
-        else:
-            return _DATABASE
+    def __new__ (cls, type = None):
+        if not '_the_instance' in cls.__dict__:
+            dbcls = cls._generate(type)
+            cls._the_instance = dbcls(cls._get_session())
+        elif type is not None:
+            raise DatabaseInstantiationError("Database instantiation called with 'type' argument multiple times.")
+        return cls._the_instance
     
-    if _SESSION is None:
-        _SESSION = Session("db.cfg", name = "DB")
-        _SESSION.load()
+    @classmethod
+    def _generate(cls, type):
 
-    _TYPE = type
+        if type is None:
+            warning("No database type specified! Falling back to default.")
+            type = cls.DEFAULT
+        
+        cls.DB_TYPE = type
 
-    if type == "sql":
-        debug("Using SQLDatabase")
-        try:
-            from .sql import SQLDatabase
-        except ImportError:
-            warning(_("Cannot load %s."), "SQLDatabase")
-            _DATABASE = Database("dict")
-        else:
-            _DATABASE = SQLDatabase(SectionDict(_SESSION, type))
+        if type == "sql":
+            debug("Using SQLDatabase")
+            try:
+                from .sql import SQLDatabase
+            except ImportError:
+                warning(_("Cannot load %s."), "SQLDatabase")
+                return cls._generate("dict")
+            else:
+                return SQLDatabase
 
-    elif type == "dict":
-        debug("Using HashDatabase")
-        from .hash import HashDatabase
-        _DATABASE = HashDatabase(SectionDict(_SESSION, type))
-    
-    elif type == "eixsql":
-        debug("Using EixSQLDatabase")
-        try:
-            from .eix_sql import EixSQLDatabase
-        except ImportError:
-            warning(_("Cannot load %s."), "EixSQLDatabase.")
-            _DATABASE = Database("sql")
-        else:
-            _DATABASE = EixSQLDatabase(SectionDict(_SESSION, type))
+        elif type == "dict":
+            debug("Using HashDatabase")
+            from .hash import HashDatabase
+            return HashDatabase
+        
+        elif type == "eixsql":
+            debug("Using EixSQLDatabase")
+            try:
+                from .eix_sql import EixSQLDatabase
+            except ImportError:
+                warning(_("Cannot load %s."), "EixSQLDatabase.")
+                return cls._generate("sql")
+            else:
+                return EixSQLDatabase
 
-    else:
-        error(_("Unknown database type: %s"), type)
-        raise UnknownDatabaseTypeError, type
+        else:
+            error(_("Unknown database type: %s"), type)
+            raise UnknownDatabaseTypeError, type
 
-    return _DATABASE
+    @classmethod
+    def _get_session(cls):
+        return SectionDict(Session("db.cfg", name = "DB"), cls.DB_TYPE)
diff --git a/portato/db/database.py b/portato/db/database.py
index 6e92d79..c679d06 100644
--- a/portato/db/database.py
+++ b/portato/db/database.py
@@ -16,6 +16,8 @@ from threading import RLock
 from functools import wraps
 from ..helper import warning
 
+from .exceptions import UnsupportedSearchTypeError
+
 class UnsupportedSearchTypeError(Exception):
     pass
 
diff --git a/portato/db/exceptions.py b/portato/db/exceptions.py
new file mode 100644
index 0000000..8a6e424
--- /dev/null
+++ b/portato/db/exceptions.py
@@ -0,0 +1,24 @@
+# -*- coding: utf-8 -*-
+#
+# File: portato/db/exceptions.py
+# This file is part of the Portato-Project, a graphical portage-frontend.
+#
+# Copyright (C) 2006-2010 René 'Necoro' Neumann
+# This is free software.  You may redistribute copies of it under the terms of
+# the GNU General Public License version 2.
+# There is NO WARRANTY, to the extent permitted by law.
+#
+# Written by René 'Necoro' Neumann <necoro@necoro.net>
+
+class DatabaseError (Exception):
+    pass
+
+class UnknownDatabaseTypeError (DatabaseError):
+    pass
+
+class DatabaseInstantiationError (DatabaseError):
+    pass
+
+class UnsupportedSearchTypeError(DatabaseError):
+    pass
+
diff --git a/portato/db/sql.py b/portato/db/sql.py
index ea4ce91..f5dc257 100644
--- a/portato/db/sql.py
+++ b/portato/db/sql.py
@@ -120,7 +120,7 @@ class SQLDatabase (Database):
             os.remove(dbpath)
             db_existed = False
 
-        self.session["pickle"] = True # no need for a certain value
+        self.session["pickle"] = "1" # no need for a certain value
 
         if db_existed:
             debug("portdirs.db already existant")
diff --git a/portato/gui/exception_handling.py b/portato/gui/exception_handling.py
index dbafa7e..d9b133c 100644
--- a/portato/gui/exception_handling.py
+++ b/portato/gui/exception_handling.py
@@ -99,7 +99,7 @@ def convert (version):
 def get_version_infos():
     from ..constants import VERSION, REVISION
     from ..backend import system
-    from ..db import _TYPE as db_type
+    from ..db import Database
     
     if REVISION:
         VERSION = "%s (git: %s)" % (VERSION, REVISION)
@@ -109,7 +109,7 @@ def get_version_infos():
         "System: %s" % " ".join(get_runsystem()),
         "Python version: %s" % sys.version,
         "Used backend: %s" % system.get_version(),
-        "Used database type: %s" % db_type,
+        "Used database type: %s" % Database.DB_TYPE,
         "pygtk: %s (using GTK+: %s)" % (convert(gtk.pygtk_version), convert(gtk.gtk_version)),
         "pygobject: %s (using GLib: %s)" % (convert(gobject.pygobject_version), convert(gobject.glib_version))))