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Re: importing: what does "from" do?

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On Jan 21, 2016 7:31 AM, "Charles T. Smith" <cts.private.yahoo@gmail.com>
wrote:
>
> What does "from (module) import (func)" do?

Approximately equivalent to:

import module
func = module.func

Except that it doesn't bind "module" to anything.

> Please don't tell me that I shouldn't ask because real programmers
> know not to have circular dependencies ...
>
> I have no idea what was imported before.  I just want to import hexdump().
> Unfortunately, this does not work:
>
>   from utilities import hexdump
>
>     ImportError: cannot import name hexdump

What is utilities? Is it a module on your sys.path?

> Now, I shouldn't have a problem because the programmers before me didn't
> understand either, and so just duplicated it everywhere, but I'd really
> like to do it right.
>
> I would have thought that "from" would allow me to import just one
> symbol.  Now, for all the people just chomping at the bit to tell
> me about circular dependencies

What makes you think this is caused by circular dependencies? It could be,
but you really haven't given us enough information about what utilities is
to diagnose that.

> would you explain to me why I get this:
>
>   (PDB)hexdump(msg)
> *** NameError: name 'hexdump' is not defined

Probably because the name 'hexdump' is not defined.

> P.S. can I get a list of all the loaded symbols and/or modules?

What do you mean by "loaded"? Bound to a name in the main module? In the
globals of the current scope? In any module? Try the "dir" or "vars"
built-in.

You can get a view of all the *cached* modules by looking in the
sys.modules dict.

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importing: what does "from" do? "Charles T. Smith" <cts.private.yahoo@gmail.com> - 2016-01-21 14:20 +0000
  Re: importing: what does "from" do? Ian Kelly <ian.g.kelly@gmail.com> - 2016-01-21 07:52 -0700
    Re: importing: what does "from" do? "Charles T. Smith" <cts.private.yahoo@gmail.com> - 2016-01-21 15:12 +0000
      Re: importing: what does "from" do? Ian Kelly <ian.g.kelly@gmail.com> - 2016-01-21 08:59 -0700
        Re: importing: what does "from" do? "Charles T. Smith" <cts.private.yahoo@gmail.com> - 2016-01-21 16:30 +0000
          Re: importing: what does "from" do? "Charles T. Smith" <cts.private.yahoo@gmail.com> - 2016-01-21 16:41 +0000
      Re: importing: what does "from" do? Steven D'Aprano <steve@pearwood.info> - 2016-01-22 03:22 +1100
  Re: importing: what does "from" do? John Gordon <gordon@panix.com> - 2016-01-21 15:31 +0000
    Re: importing: what does "from" do? "Charles T. Smith" <cts.private.yahoo@gmail.com> - 2016-01-21 15:37 +0000
      Re: importing: what does "from" do? John Gordon <gordon@panix.com> - 2016-01-21 15:44 +0000
        Re: importing: what does "from" do? "Charles T. Smith" <cts.private.yahoo@gmail.com> - 2016-01-21 15:46 +0000
          Re: importing: what does "from" do? John Gordon <gordon@panix.com> - 2016-01-21 15:59 +0000
        Re: importing: what does "from" do? "Charles T. Smith" <cts.private.yahoo@gmail.com> - 2016-01-21 15:53 +0000
          Re: importing: what does "from" do? Steven D'Aprano <steve@pearwood.info> - 2016-01-22 03:28 +1100
  Re: importing: what does "from" do? Rustom Mody <rustompmody@gmail.com> - 2016-01-21 23:03 -0800
    Refactoring in a large code base (was: importing: what does "from" do?) Ben Finney <ben+python@benfinney.id.au> - 2016-01-22 18:54 +1100
      Re: Refactoring in a large code base Marko Rauhamaa <marko@pacujo.net> - 2016-01-22 10:29 +0200
        Re: Refactoring in a large code base Rustom Mody <rustompmody@gmail.com> - 2016-01-22 01:21 -0800
          Re: Refactoring in a large code base Marko Rauhamaa <marko@pacujo.net> - 2016-01-22 12:19 +0200
            Re: Refactoring in a large code base Chris Angelico <rosuav@gmail.com> - 2016-01-22 22:19 +1100
              Re: Refactoring in a large code base Marko Rauhamaa <marko@pacujo.net> - 2016-01-22 13:54 +0200
                Re: Refactoring in a large code base Chris Angelico <rosuav@gmail.com> - 2016-01-22 23:28 +1100
                Re: Refactoring in a large code base Marko Rauhamaa <marko@pacujo.net> - 2016-01-22 15:00 +0200
                Re: Refactoring in a large code base Chris Angelico <rosuav@gmail.com> - 2016-01-23 00:26 +1100
                Re: Refactoring in a large code base Marko Rauhamaa <marko@pacujo.net> - 2016-01-22 15:48 +0200
                Re: Refactoring in a large code base Chris Angelico <rosuav@gmail.com> - 2016-01-23 01:09 +1100
              Re: Refactoring in a large code base Rustom Mody <rustompmody@gmail.com> - 2016-01-22 04:04 -0800
                Re: Refactoring in a large code base Marko Rauhamaa <marko@pacujo.net> - 2016-01-22 14:21 +0200
                Re: Refactoring in a large code base Thomas Mellman <tmellman@web.de> - 2016-01-22 12:27 +0000
                Re: Refactoring in a large code base Chris Angelico <rosuav@gmail.com> - 2016-01-22 23:34 +1100
                Re: Refactoring in a large code base Rustom Mody <rustompmody@gmail.com> - 2016-01-22 05:30 -0800
                Re: Refactoring in a large code base Marko Rauhamaa <marko@pacujo.net> - 2016-01-22 15:43 +0200
                Re: Refactoring in a large code base Rustom Mody <rustompmody@gmail.com> - 2016-01-22 05:58 -0800
                Re: Refactoring in a large code base Chris Angelico <rosuav@gmail.com> - 2016-01-23 01:08 +1100
            Re: Refactoring in a large code base "Charles T. Smith" <cts.private.yahoo@gmail.com> - 2016-01-22 11:45 +0000

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