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+--- Thread: Memory Location, Object Attributes and how to use them (/thread-34694.html)
Memory Location, Object Attributes and how to use them - Meld51 - Aug-22-2021
Here's something fundamental that I don't understand about the Object Oriented paradigm and I could do with some discussion on this. Obviously I am a novice but I am studying UK A level Computer Science so I'm a year into Python coding.
I can easily create a class and provide it with some instance attributes.
I can create a number of objects and print a memory location for each one (this shows me that each object is distinct with it's own location).
I can print the object attributes.
It seems quite common to copy the object attributes into a list or a dictionary for processing elsewhere.
What I don't understand is this:
How do I alter the object attributes in the object (in memory) rather than in the resulting list?
Do I even need to do that?
I can't see through this. When I look at example code here and there, I see that the list might be upgraded but that's not the object is it...it's a list! How do I get back to an object in memory and change that? I'm not even sure if I would need to do that but why create an object in memory if you don't want to work on it somewhere along the line. Why not just work on a list in the first place?
It is common to save the list of object attributes to a file so they can be reused later but when they are reloaded, are they objects or are they just a list of attributes?
I know this is rather fundamental but I don't understand it and I want to.
I don't think I need to upload any code for this question but I can provide some if needed. Let me know
Thanks in advance
RE: Memory Location, Object Attributes and how to use them - Yoriz - Aug-22-2021
The list holds a pointer to the objects they are not copies of the object.
class TestClass:
def __init__(self, value):
self.value = value
test_classes = [TestClass(number) for number in range(5)]
for test_class in test_classes:
print(test_class.value)
test_class5 = TestClass(5)
test_classes.append(test_class5)
print(test_classes[5] is test_class5)
print(test_classes[5])
print(test_class5)
test_class5.value = 20
print(test_class5.value)
print(test_classes[5].value)Output:0
1
2
3
4
True
<__main__.TestClass object at 0x000001F1B4CD8B20>
<__main__.TestClass object at 0x000001F1B4CD8B20>
20
20