hello,
I tried to find an easy way to add properties (attributes) to a number
of different components.
So I wrote a class, from which all these components are derived.
By trial and error I created the code below, which now works, but
there is one thing I don't understand:
in the line indicated with "<<== 1" I'm not allowed to use
for item in self.extra_getters :
because it will result in an infinite recursion.
But in the line indicated with "<<== 2" , I am allowed ...
... why is this allowed ??
thanks,
Stef Mientki
# ***********************************************************************
# ***********************************************************************
class _add_attribs ( object ) :
def __init__ ( self ) :
self.extra_setters = {}
self.extra_getters = {}
def _add_attrib ( self, text, setter = None, getter = None ) :
if setter :
self.extra_setters [ text ] = setter
if getter :
self.extra_getters [ text ] = getter
# *********************************************************
# always called instead of the normal mechanism
# *********************************************************
def __setattr__ ( self, attr, value ) :
for item in self.extra_setters :
if item == attr :
self.extra_setters [ item ] ( value )
break
else :
self.__dict__[attr] = value
# *********************************************************
# only called when not found with the normal mechanism
# *********************************************************
def __getattr__ ( self, attr ) :
try :
for item in self.__dict__['extra_getters'] : <<== 1
if item == attr :
return self.extra_getters [ item ] ( ) <<== 2
except :
return []
# ***********************************************************************
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