From 3b2bafdf12f8e18d8565e094c506152952891f48 Mon Sep 17 00:00:00 2001
From: Laurent Bachelier <laurent@bachelier.name>
Date: Tue, 27 Mar 2012 12:08:33 +0200
Subject: [PATCH] Centralize "empty" comparisons

And always use "is" instead of "==".
---
 weboob/applications/videoob/videoob.py       |  6 ++---
 weboob/capabilities/base.py                  | 24 +++++++++++++-------
 weboob/tools/application/formatters/table.py |  7 +++---
 3 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/weboob/applications/videoob/videoob.py b/weboob/applications/videoob/videoob.py
index 6e865a11..75f9fe10 100644
--- a/weboob/applications/videoob/videoob.py
+++ b/weboob/applications/videoob/videoob.py
@@ -24,7 +24,7 @@ import sys
 import os
 
 from weboob.capabilities.video import ICapVideo, BaseVideo
-from weboob.capabilities.base import NotLoaded, NotAvailable
+from weboob.capabilities.base import empty
 from weboob.tools.application.repl import ReplApplication
 from weboob.tools.application.media_player import InvalidMediaPlayer, MediaPlayer, MediaPlayerNotFound
 from weboob.tools.application.formatters.iformatter import IFormatter
@@ -49,9 +49,9 @@ class VideoListFormatter(IFormatter):
         else:
             result = u'%s* (%s) %s%s\n' % (self.BOLD, item['id'], item['title'], self.NC)
         result += '            %s' % (item['duration'] if item['duration'] else item['date'])
-        if item['author'] not in (NotLoaded, NotAvailable, None):
+        if not empty(item['author']):
             result += ' - %s' % item['author']
-        if item['rating'] not in (NotLoaded, NotAvailable, None):
+        if not empty(item['rating']):
             result += u' (%s/%s)' % (item['rating'], item['rating_max'])
         return result
 
diff --git a/weboob/capabilities/base.py b/weboob/capabilities/base.py
index feb650cb..869642fe 100644
--- a/weboob/capabilities/base.py
+++ b/weboob/capabilities/base.py
@@ -28,7 +28,19 @@ from weboob.tools.ordereddict import OrderedDict
 
 __all__ = ['FieldNotFound', 'NotAvailable', 'NotLoaded', 'IBaseCap',
            'Field', 'IntField', 'FloatField', 'StringField', 'BytesField',
-           'DateField', 'DeltaField', 'CapBaseObject']
+           'DateField', 'DeltaField', 'CapBaseObject', 'empty']
+
+
+def empty(value):
+    """
+    Checks if a value is empty (None, NotLoaded or NotAvailable).
+
+    :rtype: :class:`bool`
+    """
+    for cls in (None, NotLoaded, NotAvailable):
+        if value is cls:
+            return True
+    return False
 
 
 class FieldNotFound(Exception):
@@ -278,8 +290,7 @@ class CapBaseObject(object):
         :param excepts: if specified, do not change fields listed
         """
         for key, old_value in self.iter_fields():
-            if old_value in (None, NotLoaded, NotAvailable) and \
-               not key in excepts:
+            if empty(old_value) and key not in excepts:
                 setattr(self, key, value)
 
     def iter_fields(self):
@@ -314,7 +325,7 @@ class CapBaseObject(object):
         except KeyError:
             object.__setattr__(self, name, value)
         else:
-            if value not in (NotLoaded, NotAvailable, None):
+            if not empty(value):
                 try:
                     # Try to convert value to the wanted one.
                     nvalue = attr.convert(value)
@@ -329,10 +340,7 @@ class CapBaseObject(object):
                     # raise ValueError.
                     pass
 
-            if not isinstance(value, attr.types) and \
-               value is not NotLoaded and \
-               value is not NotAvailable and \
-               value is not None:
+            if not isinstance(value, attr.types) and not empty(value):
                 raise ValueError(
                     'Value for "%s" needs to be of type %r, not %r' % (
                         name, attr.types, type(value)))
diff --git a/weboob/tools/application/formatters/table.py b/weboob/tools/application/formatters/table.py
index 86d59844..5baf5ceb 100644
--- a/weboob/tools/application/formatters/table.py
+++ b/weboob/tools/application/formatters/table.py
@@ -20,7 +20,7 @@
 
 from prettytable import PrettyTable
 
-from weboob.capabilities.base import NotLoaded, NotAvailable
+from weboob.capabilities.base import empty
 
 from .iformatter import IFormatter
 
@@ -52,7 +52,7 @@ class TableFormatter(IFormatter):
         for i in xrange(len(self.keys)):
             available = False
             for line in self.queue:
-                if line[i] is not NotLoaded and line[i] is not NotAvailable and line[i] is not None:
+                if not empty(line[i]):
                     available = True
                     break
             if available:
@@ -63,7 +63,7 @@ class TableFormatter(IFormatter):
         s = ''
         if self.display_header and self.header:
             if self.HTML:
-                s+= '<p>%s</p>' % self.header
+                s += '<p>%s</p>' % self.header
             else:
                 s += self.header
             s += "\n"
@@ -92,5 +92,6 @@ class TableFormatter(IFormatter):
     def set_header(self, string):
         self.header = string
 
+
 class HTMLTableFormatter(TableFormatter):
     HTML = True