dictionaries link

Question

I'm new to dictionaries and have found the following to be very confusing.

resume = [{'name': 'New', 'value1': 'dfgdf'}, {'name': 'garry', 'value1': 'hhhhhh'}]
current = resume[0]
current['name'] = '24/7 link was not requested...'
print(resume)

Returns:

[{'name': '24/7 link was not requested...', 'value1': 'dfgdf'}, {'name': 'garry', 'value1': 'hhhhhh'}]

Why is this happening when a permanent/continuous link between resume and current was not requested? ...... and how can I change this so that current['name'] will update to the new/requested string value and not resume.

yes it is, but when i change the values in `current` with `current['name']` ... the value in `resume` should not change. I did not ask for that. — Rhys, Sep 29 '18 at 19:58
Is the issue that you don't want to modify the first element in `resume`? If so, you can do `current = resume[0].copy()` to get a copy of the first element instead. More on that [here](https://stackoverflow.com/questions/23852480/assigning-value-in-python-dict-copy-vs-reference) — jDo, Sep 29 '18 at 20:00
I would also suggest reading about it in here: https://realpython.com/copying-python-objects/ — Adelina, Sep 29 '18 at 20:01
@Rhys yes, you **did** ask for that. Please read https://nedbatchelder.com/text/names.html And this has nothing to do with dictionaries, this is how assignment works for *all objects in Python* — juanpa.arrivillaga, Sep 29 '18 at 20:03

score 3 · Accepted Answer · answered Sep 29 '18 at 20:00

3

Try changing

current = resume[0]

to

current = resume[0].copy()

This should create a new dictionary object.

answered Sep 29 '18 at 20:00

Sebiancoder

104
2
10

thanks for this, I'll test it in a little while. Lists can do this without `.copy()` ... what purpose does it serve to include this link by default =/ – Rhys Sep 29 '18 at 20:06
No, lists have the *same* behaviour. Read the link that juanpa posted. – Daniel Roseman Sep 29 '18 at 20:08
@Rhys no, **everything in Python works like this**. – juanpa.arrivillaga Sep 29 '18 at 20:09
wow, you're right. I'd never seen that before – Rhys Sep 29 '18 at 20:12
I'll mark this as correct. Works for lists and dictionaries. for the record it drove me crazy. it adds complexity to basic instructions – Rhys Sep 29 '18 at 20:16

dictionaries link

1 Answers1