Speed up properties?!

[david mugnai]

Dr. Peer Griebel wrote:

> Andrew Bennetts wrote:
> 
>> On Fri, May 14, 2004 at 07:48:29AM +0200, Dr. Peer Griebel wrote:
>>
>>> Hi,
>>>
>>> I have a class with some properties.  I would like to verify that only
>>> valid values are assigned to the properties using assert.  Therefore I
>>> code setters and getters and use property() to convert these to have a
>>> real property.
>>>
>>> Since the verification is only performed in __debug__ runs the
>>> property() is quite a lot of overhead.  I tried to circumvent it.  This
>>> is my result so far:
What do you think about this:

import types

class Meta1(type):
     def __new__(mcl,classname,bases,classdict):
         if not __debug__:
             return type.__new__(mcl,classname,bases,classdict)

         GetterName="_%s__get_" % classname
         SetterName="_%s__set_" % classname

         Properties={}
         for x in classdict:
             if isinstance(classdict[x],types.FunctionType):
                 if x.startswith(GetterName):
                     name=x[len(GetterName):]
                     Properties[name]=property(classdict[x],
                                 classdict[SetterName+name])

         classdict.update(Properties)
         return type.__new__(mcl,classname,bases,classdict)

class A(object):
     __metaclass__=Meta1

     def __init__(self):
         self.x=5

     def __get_x(self):
         return self._x
     def __set_x(self,value):
         if value>5:
             raise ValueError,value
         self._x=value

S=A()
print S.x
S.x=12
print S.x

---------------------------

HTH
dvd

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