Alexander wrote:
On 17.04.2010 18:32, Steven D'Aprano wrote:
On Sat, 17 Apr 2010 13:09:43 +0400, Alexander wrote:
Hi, list.
I've some nontrivial class implementation MyClass and its instance my:
my = MyClass(args)
MyClass uses in internals some variable which is not defined in MyClass
itself. I want to extend instance of MyClass at runtime defining this
variable and making new instance. It is like a class inheritance in a
static way
I'm afraid I don't understand what you are asking. MyClass uses a
variable which is not defined in MyClass. Where is it defined? Is it a
global variable?
What do you mean, "like a class inheritance in a static way"?
Perhaps you should give an example of what you want to happen.
Ok, I'll try to explain on the following example. Let's consider class
MyClass that holds one string and concatenate it with other not defined
in this class:
class MyClass(object):
def __init__(s): pass
def set(s, key):
s.__key = key
def __str__(s):
return s.__key + ' ' + s.__other
def new(s, value):
return SubClass(s, value)
The problem is how to implement class SubClass which inherits MyClass,
define new variable __other accessible from MyClass intance and with
working application:
a = MyClass()
a.set('key1')
b1 = a.new('value1')
b2 = a.new('value2')
print b1, "," ,b2 # give 'key1 value1 , key1 value2'
a.set('key2')
print b1, ",", b2 # give 'key2 value1 , key2 value2'
Unfortunately I'm not sure you description clarifies anything.
My *guess* is that you would need a Factory class.
class Factory: # this is a Factory class
class MyClass: # the class you actually need
redFactory = Factory('red')
blueFactory = Factory('blue')
ex1 = redFactory.new('value1') # use the factory to return an instance
of MyClass initialized with the proper parameters
ex2 = blueFactory.new('value1')
print ex1
'red value1'
print ex2
'blue value1'
Is that want you want to do ? If so, I may elaborate a little more...
JM
--
http://mail.python.org/mailman/listinfo/python-list
