[Tutor] Trying to understand how object re-instantiation gets propagated

[Dimitar Ivanov]

Hi all,

Apologies if this isn't the correct place to ask, I'm running into a rather
curious situation that I'm trying to fully grasp and so far my logic is
failing me so I hope maybe you could help clear up my confusion. :)

I have a small Python program that works with JIRA issues, I've created my
own class that works on top of the Python jira package
<https://pypi.org/project/jira/> as means to have easier access to the
fields I require. While this setup isn't directly related to my question
and I suspect you could easily recreate my situation with any OOP setup, I
feel like it's necessary to mention what I'm doing.

My JIRA issue class (shown below) retrieves the values from a JIRA server
and saves them as instance variables. To avoid outdated information when I
update a value on the JIRA server, I made a small function that retrieves
the JIRA issue from the server again and re-instantiates a new object of my
class:

def main():
  jira_issue = jira_connection.issue("ISSUE-1")    # Retrieving the issue
from the JIRA server
  my_issue = JiraIssue(jira_issue)
  print(my_issue.assignee)
  # Output is "Unassigned"
  # Go in JIRA and change the assignee to 'Foobar' now
  my_issue.reload()
  print(my_issue.assignee)
  # Output now is "Foobar"

class JiraIssue:
  def __init__(self, jira_issue):
    self.key = issue.key
    self.assignee = issue.fields.assignee

  def reload(self):
    jira_issue = jira_connection.issue(self.key)    # Retrieving the issue
from the JIRA server
    issue = JiraIssue.__init__(self, jira_issue)
    return issue


At this point, my logic tells me that once I have invoked
'my_issue.reload()', I should have assigned its return value to a variable
in order to gain access to the object that was re-instantiated but instead
Python just "knows" that my_issue is now referring to the newly
instantiated object by the reload() method.

So, my question is - how does this happen? How does the interpreter know of
the new object and automatically assigns it to my_issue?

Thanks a lot in advance! :)

Regards,
Dimitar