slapos/recipe/librecipe/generic.py: GenericBaseRecipe's _ws is a lazy attribute now.

getWorkingSet() is slow and it is not always needed. So, it is better not to call it in __init__.

slapos/recipe/librecipe/generic.py

@@ -61,7 +61,13 @@ class GenericBaseRecipe(object):
     self._options(options) # Options Hook
     self.options = options.copy() # Updated options dict
 
-    self._ws = self.getWorkingSet()
+  @property
+  def _ws(self):
+    # getWorkingSet() is slow and it is not always needed.
+    # So _ws should be a lazy attribute.
+    if getattr(self, '__ws', None) is None:
+      self.__ws = self.getWorkingSet()
+    return self.__ws
 
   def update(self):
     """By default update method does the same thing than install"""

[Vincent Pelletier]

Beware of __ magic:

>>> class Foo(object):
...   def foo(self):
...     if getattr(self, '__bar', None) is None:
...       print 'miss'
...       self.__bar = 1
...     else:
...       print 'hit'
...
>>> a = Foo()
>>> a.foo()
miss # As expected
>>> a.foo()
miss # Not expected !
>>> a.__dict__
{'_Foo__bar': 1}
>>> setattr(a, '__bar', 2)
>>> a.__dict__
{'__bar': 2, '_Foo__bar': 1}
>>> a.foo()
hit # And here it is, but we have two property with apparently the same name now, and depending on how they are accessed, one or the other will be returned.

IOW, in a class, a.__b != getattr(a, '__b').

The same code ran outside of a class would work though:

>>> b = Foo()
>>> b.__bar = 1
>>> b.foo()
hit
>>> b.__dict__
{'__bar': 1}

[Yusei Tahara]

Thank you. I fixed it.