Object Instatiation Issue. I think.

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February 13th, 2013, 12:57 PM

Mr909

Contributing User

Join Date: Dec 2012

Posts: 32

Time spent in forums: 1 h 53 m 20 sec
Reputation Power: 1

Object Instatiation Issue. I think.

Okay, so I have an object structure that is as follows:

"Card", the container object-
---Node_Container, a dict object initialized when Card is created.
------Composite(node,list) that is added afterwards.

For some reason, whenever I instantiate two cards, each has a different Node_Container, but both seem to contain the same composite node. Whenever I make changes to one, it makes changes to the other.

The code's kind of awkward due to some placeholders, but here's what I have so far:

Code:

raw_list=['PYR','CP']

class node_container(dict):
	pass

class card():
	name=str()
	nodes=node_container()
	def __repr__(self):
		return self.name

class node():
	pass

class pouch(dict):
	def __init__(self):
		for item in raw_list:
			self[item] = 0

class composite(node,list):
	def parse(self):
		raw_val = pouch()
		compos = list(self)
		while len(compos) > 0:
			nxt=compos.pop(0)
			print nxt
			item,amt = nxt[0],nxt[1]
			if item in raw_list:
				raw_val[item] += amt
			if item in index.keys():
				ref = index[item]
				compos += ref.nodes['comp']
		return raw_val

master_folio,index=list(),dict()

def new_card(indval,cname):
	new = card()
	master_folio.append(new)
	new.name = cname
	index[indval] = new
	return new

wk = new_card('STN-POW-001','Strike I')
wk.nodes['comp']=composite([['PYR',20],['CP',10]])

wk = new_card('STN-POW-002','Strike II')
wk.nodes['comp']=composite([['CP',20],['PYR',15],['STN-POW-001',1]])

And, running it in IDLE, here is an example of the error:

Code:

>>> index
{'STN-POW-001': Strike I, 'STN-POW-002': Strike II}

Okay, so I know the index does contain two separate cards... 

>>> master_folio
[Strike I, Strike II]

Likewise, each instance seems to have been instantiated correctly with new_card(). 

>>> index['STN-POW-002'].nodes['comp']
[['CP', 20], ['PYR', 15], ['STN-POW-001', 1]]

Okay, good. That should be the composite values for Strike II. 

>>> index['STN-POW-001'].nodes['comp']
[['CP', 20], ['PYR', 15], ['STN-POW-001', 1]]

Okay, here's the problem. For some reason,  changing the composite for one in the main code changed the composite for the other. 

>>> master_folio[0]==master_folio[1]
False

The objects ARE different. They just seem to copy off the nodes list. 

>>> index['STN-POW-001'].nodes['comp'] = composite([['PYR',20],['CP',10]])
>>> index['STN-POW-001'].nodes['comp']
[['PYR', 20], ['CP', 10]]

Okay. It's changed correctly. 

>>> index['STN-POW-002'].nodes['comp']=composite([['CP',20],['PYR',15],['STN-POW-001',1]])
>>> index['STN-POW-002'].nodes['comp']
[['CP', 20], ['PYR', 15], ['STN-POW-001', 1]]

Okay. Now we know this one is good too. 

>>> index['STN-POW-001'].nodes['comp']
[['CP', 20], ['PYR', 15], ['STN-POW-001', 1]]

Why did this one change!? The two instances the dictionary refers to are separate.

I hope that serves as adequate explanation.

February 13th, 2013, 04:05 PM

b49P23TIvg

Contributing User

Join Date: Aug 2011

Posts: 3,389

Time spent in forums: 1 Month 2 Weeks 3 Days 14 h 22 m 25 sec
Reputation Power: 383

The issue concerns class attributes versus object attributes, I think. Altering your program slightly to show id(nodes) in several places you'll see that it's always the same, as it should be. Or I misunderstand your concern.

Code:

raw_list=['PYR','CP']

class node_container(dict):  # dict
    pass

class card():
    name=str()             # class instances name is ''
    nodes=node_container() # class instances nodes is a dict
    print('{}: id nodes'.format(id(nodes)))
    def __repr__(self):
        return self.name

class node(): # a storage area
    pass

class pouch(dict):  # dict with some items initialized to 0

    def __init__(self):  # raw_list=['PYR','CP']
        for item in raw_list:
            self[item] = 0

class composite(node,list):

    def parse(self):
        raw_val = pouch()
        compos = list(self)
        while len(compos) > 0:
            nxt=compos.pop(0)
            print(nxt)
            item,amt = nxt[0],nxt[1]
            if item in raw_list:
                raw_val[item] += amt
            if item in index.keys():
                ref = index[item]
                compos += ref.nodes['comp']
        return raw_val


(master_folio,index,) = (list(),dict(),)

def new_card(indval,cname):
    new = card()
    master_folio.append(new)
    new.name = cname
    index[indval] = new
    return new

wk = new_card('STN-POW-001','Strike I')
wk.nodes['comp']=composite([['PYR',20],['CP',10]])
print('{}: id wk.nodes'.format(id(wk.nodes)))

wk = new_card('STN-POW-002','Strike II')
wk.nodes['comp']=composite([['CP',20],['PYR',15],['STN-POW-001',1]])
print('{}: id wk.nodes'.format(id(wk.nodes)))

print('''{}: id index['STN-POW-002'].nodes'''.format(id(index['STN-POW-002'].nodes)))
print('''{}: id index['STN-POW-001'].nodes'''.format(id(index['STN-POW-001'].nodes)))

Output:
$ ( cd /tmp && python p.py )
21736128: id nodes
21736128: id wk.nodes
21736128: id wk.nodes
21736128: id index['STN-POW-002'].nodes
21736128: id index['STN-POW-001'].nodes
$
$
$
$ ( cd /tmp && python3 p.py )
19115088: id nodes
19115088: id wk.nodes
19115088: id wk.nodes
19115088: id index['STN-POW-002'].nodes
19115088: id index['STN-POW-001'].nodes
$

Code:

class module_scope:
    class_scope = list()
    def __init__(self):
        self.object_scope = True

def f():
    global global_scope
    local_scope = 'defined in f'

__________________
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February 13th, 2013, 05:01 PM

Mr909

Contributing User

Join Date: Dec 2012

Posts: 32

Time spent in forums: 1 h 53 m 20 sec
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Okay, yeah, the issue is it SHOULDN'T be doing that.

When I call the card:

Code:

class card():
        name=str()
        nodes=node_container()

From my understanding, since I put parenthesis after node_container, it instantiates a separate dictionary for each object (or, rather, it should). Just like it has it's own name, it should have it's own unique node container. That's what I need it to do; I'm using a dictionary instead of a list so that I can ensure that A. The nodes in the node container are a set, none of which are replicated and B. I can call them without explicitly knowing their order (like I call wk.nodes['comp'] all the time) Currently, only the composition node is present, but as you can see there are placeholders for more.

So, is there a way to instantiate separate node_container() objects, one for each card?

February 13th, 2013, 05:41 PM

b49P23TIvg

Contributing User

Join Date: Aug 2011

Posts: 3,389

Time spent in forums: 1 Month 2 Weeks 3 Days 14 h 22 m 25 sec
Reputation Power: 383

() following node_container cause the callable to be called. Create this file, and import it into python. It prints a message because the class runs all it's next-level block code on import.

Code:

class node_container(dict):
    pass

class card():
    nodes=node_container() # this happens once, on import
    print('nodes: {}'.format(nodes))

    def __init__(self):
        self.nodes = node_container()  # local to the object.  This statement executes for each new card object object.
        print('__init__ executes, object local nodes is {}'.format(self.nodes))

Last edited by b49P23TIvg : February 13th, 2013 at 05:43 PM.

February 13th, 2013, 06:56 PM

Mr909

Contributing User

Join Date: Dec 2012

Posts: 32

Time spent in forums: 1 h 53 m 20 sec
Reputation Power: 1

Okay, I think I get it now. Thank you very much.

Object Instatiation Issue. I think.

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