On May 12, 10:04 pm, Terry Reedy <tjre...@udel.edu> wrote:
> On 5/12/2011 9:11 AM, JamesEM wrote:
>
>
>
> > I would prefer to generate the properties code dynamically from the
> > keys of the dictionaries.
> > What I am looking for is something like:
>
> > class MyClass(object):
>
> > def __init__(self):
> > self.d = {}
> > d['field1'] = 1.0
> > d['field2'] = 'A'
> > d['field3'] = [10.0,20.0,30.0]
> > for f in d:
> > create_property(f)
>
> > where create_property(f) dynamically creates the property code for
> > field f in MyClass.
>
> > Is this possible?
>
> Without actually trying, I am not sure, but I believe maybe (possibly
> version dependent). The init method is the wrong place. Create the
> properties exactly once, just after the class is created. It is possible
> to add functions to classes as attributes (instance methods) after they
> are created. The property decorators *might* require that they be
> invoked with the class body, I do not know. I would first try with
> property().
>
> Assuming dict name 'd' is fixed:
>
> def gsd(key):
> def get(self):
> return self.d[key]
> def set(self, value):
> self.d[key] = value
> def del(self):
> del self.d[key]
> return get,set,del
>
> for key in fieldnames:
> setattr(MyClass, key, property(*gsd(key)))
>
> For recent versions, this could be done within a class decorator, but
> that is only convenient syntactic sugar.
>
> --
> Terry Jan Reedy
Thanks for your help.
I tried the above for get and set which worked as desired. However,
the del did not seem to work for me (using python 2.6.5).
I hope I did not mistype anything, but it objects to def del with a
syntax error. I guess because del is a reserved word.
James
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