Scope rule pecularities

[Antoon Pardon]

Op 2004-05-12, Duncan Booth schreef <me at privacy.net>:
> Antoon Pardon <apardon at forel.vub.ac.be> wrote in 
> news:slrnca428q.1i9.apardon at trout.vub.ac.be:
>
>> IMO lacking an assignment that copies the value
>> of one object into another was a mistake and
>> which creats IMO a lot of difficulties.
>> 
>> If I have a function with an object as a paramter.
>> and this object is mutable. Now within this function
>> I find a second object with the value I want the
>> argument to have. Now I can't simply copy the
>> second object over the argument but I have to
>> copy attribute by attribute from the second object
>> into the argument.
>
> Why wouldn't you just return the second value (or a copy of it) as a result 
> from the function? That is usually a more flexible choice since it gives 
> the caller the option of either replacing the original value or using the 
> modified value somewhere different.

Well because the object could be bound with more than one name.

> Anyway, if you really need to do this then the mutable object should have 
> some sort of updateState method which takes the second object as a 
> parameter. That way the original object can have control over which 
> attributes get overwritten and which don't.

And I think it is a pain in the butt to always have to write such an
UpdateState method whenever you want one object to be copied in place
from an other.

-- 
Antoon Pardon