How to deepcopy a list of user defined lists?

[srinivasan srinivas]

Hi,
I have a class which is a subclass of builtin-type list.

#------------------------------------------------------------------------------
class clist(list):
    def __new__(cls, values, ctor):
        val = []
        for item in values:
            item = ctor(item)
            val.append(item)
       
        self = list.__new__(cls, val)
        self.__values = val
        self.__ctor = ctor
        return self
#-----------------------------------------------------------------------------------

I have a list of clists, say c1 = [clist1, clist2, clist3]
How do i deepcopy this list? I tried using copy.deepcopy() method. But i got some errors. Please suggest me.

Thanks,
Srini


Add more friends to your messenger and enjoy! Go to http://messenger.yahoo.com/invite/

 

[Steven D'Aprano]

Hi,
I have a class which is a subclass of builtin-type list.

#------------------------------------------------------------------------------
class clist(list):
    def __new__(cls, values, ctor):
        val = []
        for item in values:
            item = ctor(item)
            val.append(item)
       
        self = list.__new__(cls, val)
        self.__values = val
        self.__ctor = ctor
        return self
#-----------------------------------------------------------------------------------

I have a list of clists, say c1 = [clist1, clist2, clist3] How do i
deepcopy this list? I tried using copy.deepcopy() method. But i got some
errors. Please suggest me.

Don't tell us what the errors are, I love guessing games!!!

Let's see... is it TypeError because your class doesn't override the
list.__init__ method?

clist1 = clist([1,2,3], str)

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: list() takes at most 1 argument (2 given)


Before you get to deepcopy, you actually need to have clist work
correctly. Once you've done that, show us what error you get.