python - Closing a connection with a `with` statement -


i want have class represents imap connection , use with statement follows:

class imapconnection:     def __enter__(self):         connection = imaplib.imap4_ssl(imap_host)          try:             connection.login(mail_username, mail_pass)         except imaplib.imap4.error:             log.error('failed log in')          return connection      def __exit__(self, type, value, traceback):         self.close()  imapconnection() c:     rv, data = c.list()     print(rv, data)

naturally fails since imapconnections has no attribute close. how can store connection , pass __exit__ function when with statement finished?

you need store connection in object attributes. this: 

class imapconnection:     def __enter__(self):         self.connection = imaplib.imap4_ssl(imap_host)          try:             self.connection.login(mail_username, mail_pass)         except imaplib.imap4.error:             log.error('failed log in')          return self.connection      def __exit__(self, type, value, traceback):         self.connection.close()

you want implement list method class.

edit: realized actual problem is. when with someclass(*args, **kwargs) c c not value returned __enter__ method. c instance of someclass. that's root of problem returned connection __enter__ , assumed c said connection.


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