A List of Class Objects

[vegaseat]

This was a comment from ee_programmer in reference to one of the Python code snippets.

"""
I was expecting the first class instance to only have one dictionary entry
{'person0': 0} rather than two dictionary entries. Similar expectation with second
class instance.

How do I create and assign value to separate dictionaries for each class instance?

Thanks-
ee_programmer
"""

class Person(object):
    def __init__(self, name=None, job=None, quote=None, hash={}):
        self.name = name
        self.job = job
        self.quote = quote
        self.hash = hash

#create an empty list
personList = []

#create two class instances
personList.append(Person("Payne N. Diaz", "coach", "Without exception, there is no rule!"))
personList.append(Person("Mia Serts", "bicyclist", "If the world didn't suck, we'd all fall off!"))

# assign a single entry to the dictionary of each class instance
personList[0].hash['person0'] = 0
personList[1].hash['person1'] = 1

# print dictionary of first class instance
print personList[0].hash  # {'person0': 0, 'person1': 1}

# print dictionary of second class instance
print personList[1].hash  # {'person0': 0, 'person1': 1}

First off, hash is a poor choice for a variable name since it is also a Python function so I changed that to myhash, Secondly, be careful assigning defaults to mutable arguments like lists and dictionaries. This will work with no surprises ...

class Person(object):
    def __init__(self, name=None, job=None, quote=None, **myhash):
        self.name = name
        self.job = job
        self.quote = quote
        self.myhash = myhash

#create an empty list
personList = []

#create two class instances
personList.append(Person("Payne N. Diaz", "coach", "Without exception, there is no rule!"))
personList.append(Person("Mia Serts", "bicyclist", "If the world didn't suck, we'd all fall off!"))

# test empty myhash
print personList[0].myhash  # {}

# assign a single entry to the dictionary of each class instance
personList[0].myhash['person0'] = 0
personList[1].myhash['person1'] = 1

# print dictionary of first class instance
print personList[0].myhash  # {'person0': 0}

# print dictionary of second class instance
print personList[1].myhash  # {'person1': 1}

[ee_programmer]

Thanks for the quick help, it works as I intended. What is the name of the operator "**" before myhash? I tried to look it up but didn't find it.

Thanks-
ee_programmer

[Ene Uran]

We learned that it is only used for function arguments, and ** indicates a dictionary of variable number of key:val arguments.

[ee_programmer]

The example above showed using ** as the default value to have a separate hash for each class element,
what is the default value for having a separate list in each class element?

[a1eio]

def function(*args):
    print type(args)
    print args

function('arg1', 'arg2', 'arg3')

output

<type 'tuple'>
('arg1', 'arg2', 'arg3')

If you need a list: args = list(args)