Reclassing an instance in Python

Question

I have a class that is provided to me by an external library. I have created a subclass of this class. I also have an instance of the original class.

I now want to t

Answer 1

I'm not sure that the use of inheritance is best in this case (at least with regards to "reclassing"). It seems like you're on the right track, but it sounds like composition or aggregation would be best for this. Here's an example of what I'm thinking of (in untested, pseudo-esque code):

from copy import copy

# As long as none of these attributes are defined in the base class,
# this should be safe
class SkilledProgrammer(Programmer):
    def __init__(self, *skillsets):
        super(SkilledProgrammer, self).__init__()
        self.skillsets = set(skillsets)

def teach(programmer, other_programmer):
    """If other_programmer has skillsets, append this programmer's
       skillsets.  Otherwise, create a new skillset that is a copy
       of this programmer's"""
    if hasattr(other_programmer, skillsets) and other_programmer.skillsets:
        other_programmer.skillsets.union(programmer.skillsets)
    else:
        other_programmer.skillsets = copy(programmer.skillsets)
def has_skill(programmer, skill):
    for skillset in programmer.skillsets:
        if skill in skillset.skills
            return True
    return False
def has_skillset(programmer, skillset):
    return skillset in programmer.skillsets


class SkillSet(object):
    def __init__(self, *skills):
        self.skills = set(skills)

C = SkillSet("malloc","free","pointer arithmetic","curly braces")
SQL = SkillSet("SELECT", "INSERT", "DELETE", "UPDATE")

Bob = SkilledProgrammer(C)
Jill = Programmer()

teach(Bob, Jill)          #teaches Jill C
has_skill(Jill, "malloc") #should return True
has_skillset(Jill, SQL)   #should return False

You may have to read more about sets and arbitrary argument lists if you aren't familiar with them to get this example.