[Tutor] constructors

[Erik Price]

On Wednesday, April 10, 2002, at 03:25  AM, Danny Yoo wrote:

> copy.copy() or copy.deepcopy() should work pretty well with normal 
> Python
> classes, and by defining a __copy__() function, we can control how
> functions are cloned off.
>
> For example:
>
>
> ###
>>>> class Person:
> ...     def __init__(self, name):
> ...         self.name = name
> ...     def greet(self):
> ...         print "Hello, my name is %s" % self.name
> ...     def __copy__(self):
> ...         return Person(self.name.replace('u', 'uu'))
> ...
>>>> import copy
>>>> star = Person("luke")
>>>> star.greet()
> Hello, my name is luke
>>>> cloned_star = copy.copy(star)
>>>> cloned_star.greet()
> Hello, my name is luuke
> ###

I read the "copy" document you linked to, above, but it assumes a priori 
knowledge about cloning to some extent.  What it doesn't explain is 
-why- you would use cloning.  Karthik mentioned that it is similar to 
something done in Java, but I'm still a little confused about cloning -- 
is it simply a "special" (two-underscores) method that you can use to 
flesh out an object instance and make it unique?  That's what the 
example above, with Luke and Luuke, seems to suggest.  Or is there more 
to it?

Thank you,


Erik