Reason for not allowing import twice but allowing reload()

Newsgroups	comp.lang.python
Date	2016-02-28 22:40 -0800
Message-ID	<645cdd46-d4a4-49b3-a0d8-848608d70d73@googlegroups.com> (permalink)
Subject	Reason for not allowing import twice but allowing reload()
From	alien2utoo@gmail.com

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Hello list,

We can not import a module twice in a session of Python (subsequent attempts to import same module don't result in any error though, but it is not-effective).

However after making change to module, we can reload() it (if not reload(), we could possibly have reimport statement) to get the updates in module.

I am a newbie in Python (learning via IDLE) and trying to understand

- what is extra (special) that import does, that reload() doesn't?
- if both do the same internally and externally, why subsequent imports of same module are ineffective?
- if subsequent imports of same module in a session are not effective, why not simply flag those attempts as an error, rather than letting them go effect-less.

Kindly help me understand the reasons behind.

Regards
Sandeep

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Reason for not allowing import twice but allowing reload() alien2utoo@gmail.com - 2016-02-28 22:40 -0800
  Re: Reason for not allowing import twice but allowing reload() Chris Angelico <rosuav@gmail.com> - 2016-02-29 18:01 +1100
    Re: Reason for not allowing import twice but allowing reload() Steven D'Aprano <steve@pearwood.info> - 2016-03-01 22:18 +1100
      Re: Reason for not allowing import twice but allowing reload() Chris Angelico <rosuav@gmail.com> - 2016-03-01 22:39 +1100
        Re: Reason for not allowing import twice but allowing reload() Steven D'Aprano <steve@pearwood.info> - 2016-03-02 04:11 +1100
          Re: Reason for not allowing import twice but allowing reload() Chris Angelico <rosuav@gmail.com> - 2016-03-02 05:04 +1100
      Re: Reason for not allowing import twice but allowing reload() Ian Kelly <ian.g.kelly@gmail.com> - 2016-03-01 14:53 -0700
      Re: Reason for not allowing import twice but allowing reload() Chris Angelico <rosuav@gmail.com> - 2016-03-02 09:02 +1100
      Re: Reason for not allowing import twice but allowing reload() Ian Kelly <ian.g.kelly@gmail.com> - 2016-03-01 15:29 -0700
        Re: Reason for not allowing import twice but allowing reload() Steven D'Aprano <steve@pearwood.info> - 2016-03-02 12:19 +1100
          Re: Reason for not allowing import twice but allowing reload() Ian Kelly <ian.g.kelly@gmail.com> - 2016-03-01 19:22 -0700
            Re: Reason for not allowing import twice but allowing reload() Rustom Mody <rustompmody@gmail.com> - 2016-03-02 02:15 -0800
              Re: Reason for not allowing import twice but allowing reload() Rustom Mody <rustompmody@gmail.com> - 2016-03-02 02:19 -0800
            Re: Reason for not allowing import twice but allowing reload() Grant Edwards <invalid@invalid.invalid> - 2016-03-02 15:15 +0000
      Re: Reason for not allowing import twice but allowing reload() Chris Angelico <rosuav@gmail.com> - 2016-03-02 11:13 +1100
  Re: Reason for not allowing import twice but allowing reload() Ian Kelly <ian.g.kelly@gmail.com> - 2016-02-29 00:02 -0700
  Re: Reason for not allowing import twice but allowing reload() Chris Angelico <rosuav@gmail.com> - 2016-02-29 18:11 +1100
    Re: Reason for not allowing import twice but allowing reload() BartC <bc@freeuk.com> - 2016-02-29 15:33 +0000
      Re: Reason for not allowing import twice but allowing reload() Chris Angelico <rosuav@gmail.com> - 2016-03-01 03:05 +1100
  Correct IDLE usage (was Reason for not allowing import twice but allowing reload()) Rustom Mody <rustompmody@gmail.com> - 2016-02-29 04:42 -0800
    Re: Correct IDLE usage (was Reason for not allowing import twice but allowing reload()) Terry Reedy <tjreedy@udel.edu> - 2016-03-01 01:52 -0500
      Re: Correct IDLE usage (was Reason for not allowing import twice but allowing reload()) Rustom Mody <rustompmody@gmail.com> - 2016-03-02 07:22 -0800
        Re: Correct IDLE usage (was Reason for not allowing import twice but allowing reload()) Terry Reedy <tjreedy@udel.edu> - 2016-03-02 21:40 -0500
          Re: Correct IDLE usage (was Reason for not allowing import twice but allowing reload()) Rustom Mody <rustompmody@gmail.com> - 2016-03-02 20:07 -0800
            Re: Correct IDLE usage (was Reason for not allowing import twice but allowing reload()) Rustom Mody <rustompmody@gmail.com> - 2016-03-02 20:17 -0800
  Re: Reason for not allowing import twice but allowing reload() alien2utoo@gmail.com - 2016-02-29 05:00 -0800
  Re: Reason for not allowing import twice but allowing reload() alien2utoo@gmail.com - 2016-02-29 05:22 -0800
    Re: Reason for not allowing import twice but allowing reload() alien2utoo@gmail.com - 2016-02-29 05:25 -0800
      Re: Reason for not allowing import twice but allowing reload() Steven D'Aprano <steve@pearwood.info> - 2016-03-02 04:00 +1100
        Re: Reason for not allowing import twice but allowing reload() alien2utoo@gmail.com - 2016-03-05 04:51 -0800
          Re: Reason for not allowing import twice but allowing reload() Steven D'Aprano <steve@pearwood.info> - 2016-03-10 00:53 +1100
    Reason for not allowing import twice but allowing reload() Rustom Mody <rustompmody@gmail.com> - 2016-02-29 05:51 -0800
      Re: Reason for not allowing import twice but allowing reload() alien2utoo@gmail.com - 2016-02-29 07:13 -0800
    Re: Reason for not allowing import twice but allowing reload() Terry Reedy <tjreedy@udel.edu> - 2016-03-01 02:04 -0500
  Re: Reason for not allowing import twice but allowing reload() alien2utoo@gmail.com - 2016-03-06 00:20 -0800
    Re: Reason for not allowing import twice but allowing reload() Steven D'Aprano <steve@pearwood.info> - 2016-03-07 01:50 +1100
  Re: Reason for not allowing import twice but allowing reload() alien2utoo@gmail.com - 2016-03-06 00:31 -0800

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