Re: What should Python apps do when asked to show help?

From	Random832 <random832@fastmail.com>
Newsgroups	comp.lang.python
Subject	Re: What should Python apps do when asked to show help?
Date	2016-04-30 01:20 -0400
Message-ID	<mailman.257.1461993614.32212.python-list@python.org> (permalink)
References	(10 earlier) <1461983791.3302675.593974129.5625C3C3@webmail.messagingengine.com> <85bn4rizf3.fsf@benfinney.id.au> <mailman.252.1461984570.32212.python-list@python.org> <5724253e$0$22142$c3e8da3$5496439d@news.astraweb.com> <1461993611.3340362.594023513.1E745BA1@webmail.messagingengine.com>

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On Fri, Apr 29, 2016, at 23:23, Steven D'Aprano wrote:
> Seriously, I'm thinking that a keyword argument to help might be useful:
> 
> help(object, pager=None)

I'd call it something more generic like "output".

> where:
> 
> - pager=None gives the current behaviour;
> 
> - pager="foo" calls out to the external program "foo";
> 
> - pager=callable passes the help text to callable().
> 
> 
> pager=print would do exactly what people are asking for, and you could
> then
> create your own wrapper to change the default:
> 
> help = functools.partial(builtins.help, pager=print)
> 
> 
> I think that would make it easier to test help(). Thoughts?

For testing purposes, help could return the result of the output
function, so that you can use lambda x: x to have it return the help
text.

More general thoughts: It might also be useful to move the pager
machinery from pydoc to an independent module. It's got, among other
things, a simple pager written in pure python, for use as a fallback. 

There's a lot of stuff that could be improved in the pager stuff, while
we're at it. Probably needs a single function to handle "use external
program as a pager", rather than having a bunch of logic embedded in
getpager() which only works for os.environ['PAGER'].

The "pager" function doesn't behave "properly" (in its intended behavior
of calling the expensive getpager() once when it is first called and
subsequently reusing the cached value) if a reference to it is stored
elsewhere (e.g. by importing it to another module); it should store the
cached pager function somewhere else rather than by replacing itself.

The pure-python pager only works on unix-style ttys, an analogous
function could be written for windows using msvcrt.getwch.

Thread

What should Python apps do when asked to show help? Steven D'Aprano <steve@pearwood.info> - 2016-04-29 02:33 +1000
  Re: What should Python apps do when asked to show help? alister <alister.ware@ntlworld.com> - 2016-04-28 16:45 +0000
    RE: What should Python apps do when asked to show help? Dan Strohl <D.Strohl@F5.com> - 2016-04-28 17:02 +0000
    Re: What should Python apps do when asked to show help? John Wong <gokoproject@gmail.com> - 2016-04-28 13:05 -0400
    RE: What should Python apps do when asked to show help? Dan Strohl <D.Strohl@F5.com> - 2016-04-28 17:25 +0000
    Re: What should Python apps do when asked to show help? Ethan Furman <ethan@stoneleaf.us> - 2016-04-28 10:27 -0700
  Re: What should Python apps do when asked to show help? Ethan Furman <ethan@stoneleaf.us> - 2016-04-28 09:49 -0700
  Re: What should Python apps do when asked to show help? Chris Angelico <rosuav@gmail.com> - 2016-04-29 03:06 +1000
  Re: What should Python apps do when asked to show help? Irmen de Jong <irmen.NOSPAM@xs4all.nl> - 2016-04-28 19:08 +0200
    Re: What should Python apps do when asked to show help? Marko Rauhamaa <marko@pacujo.net> - 2016-04-28 20:31 +0300
      Re: What should Python apps do when asked to show help? Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-04-29 18:04 +1200
    RE: What should Python apps do when asked to show help? Dan Strohl <D.Strohl@F5.com> - 2016-04-28 17:32 +0000
  Re: What should Python apps do when asked to show help? Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-04-28 20:30 +0300
  Re: What should Python apps do when asked to show help? Random832 <random832@fastmail.com> - 2016-04-28 13:30 -0400
  Re: What should Python apps do when asked to show help? Grant Edwards <grant.b.edwards@gmail.com> - 2016-04-28 17:33 +0000
  RE: What should Python apps do when asked to show help? Dan Strohl <D.Strohl@F5.com> - 2016-04-28 17:39 +0000
  Re: What should Python apps do when asked to show help? Random832 <random832@fastmail.com> - 2016-04-28 13:40 -0400
  Re: What should Python apps do when asked to show help? Grant Edwards <grant.b.edwards@gmail.com> - 2016-04-28 18:14 +0000
    Re: What should Python apps do when asked to show help? Marko Rauhamaa <marko@pacujo.net> - 2016-04-28 21:31 +0300
      Re: What should Python apps do when asked to show help? Grant Edwards <grant.b.edwards@gmail.com> - 2016-04-28 19:39 +0000
      Re: What should Python apps do when asked to show help? Random832 <random832@fastmail.com> - 2016-04-28 15:51 -0400
      Re: What should Python apps do when asked to show help? Grant Edwards <grant.b.edwards@gmail.com> - 2016-04-28 21:08 +0000
        Re: What should Python apps do when asked to show help? Steven D'Aprano <steve@pearwood.info> - 2016-04-29 11:40 +1000
          manpage writing [rst, asciidoc, pod] was [Re: What should Python apps do when asked to show help?] "Martin A. Brown" <martin@linux-ip.net> - 2016-04-29 06:32 -0700
          Re: manpage writing [rst, asciidoc, pod] was [Re: What should Python apps do when asked to show help?] Ethan Furman <ethan@stoneleaf.us> - 2016-04-29 07:06 -0700
            Re: manpage writing [rst, asciidoc, pod] was [Re: What should Python apps do when asked to show help?] Rustom Mody <rustompmody@gmail.com> - 2016-04-29 08:17 -0700
          Re: manpage writing [rst, asciidoc, pod] was [Re: What should Python apps do when asked to show help?] Ben Finney <ben+python@benfinney.id.au> - 2016-04-30 12:25 +1000
            Re: manpage writing [rst, asciidoc, pod] was [Re: What should Python apps do when asked to show help?] Rustom Mody <rustompmody@gmail.com> - 2016-04-29 20:20 -0700
              Re: manpage writing [rst, asciidoc, pod] was [Re: What should Python apps do when asked to show help?] Paul Rubin <no.email@nospam.invalid> - 2016-04-29 21:06 -0700
                Re: manpage writing [rst, asciidoc, pod] was [Re: What should Python apps do when asked to show help?] Rustom Mody <rustompmody@gmail.com> - 2016-04-29 23:37 -0700
                Re: manpage writing [rst, asciidoc, pod] was [Re: What should Python apps do when asked to show help?] Paul Rubin <no.email@nospam.invalid> - 2016-04-30 00:44 -0700
          Writing manual pages using Python code (was: manpage writing) Ben Finney <ben+python@benfinney.id.au> - 2016-04-30 12:25 +1000
          Re: What should Python apps do when asked to show help? cs@zip.com.au - 2016-05-01 10:06 +1000
  Re: What should Python apps do when asked to show help? Paul Rubin <no.email@nospam.invalid> - 2016-04-28 19:15 -0700
    Re: What should Python apps do when asked to show help? Rustom Mody <rustompmody@gmail.com> - 2016-04-28 22:00 -0700
      Re: What should Python apps do when asked to show help? Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-04-29 09:02 +0300
      Re: What should Python apps do when asked to show help? Steven D'Aprano <steve@pearwood.info> - 2016-04-29 19:36 +1000
        Re: What should Python apps do when asked to show help? Rustom Mody <rustompmody@gmail.com> - 2016-04-29 02:53 -0700
          Re: What should Python apps do when asked to show help? Steven D'Aprano <steve@pearwood.info> - 2016-04-30 11:20 +1000
            Re: What should Python apps do when asked to show help? Ethan Furman <ethan@stoneleaf.us> - 2016-04-29 19:09 -0700
            Re: What should Python apps do when asked to show help? Random832 <random832@fastmail.com> - 2016-04-29 22:16 -0400
              Re: What should Python apps do when asked to show help? Rustom Mody <rustompmody@gmail.com> - 2016-04-29 19:27 -0700
                Re: What should Python apps do when asked to show help? Random832 <random832@fastmail.com> - 2016-04-29 22:36 -0400
                Re: What should Python apps do when asked to show help? Rustom Mody <rustompmody@gmail.com> - 2016-04-29 19:46 -0700
                Re: What should Python apps do when asked to show help? Random832 <random832@fastmail.com> - 2016-04-29 23:14 -0400
                Re: What should Python apps do when asked to show help? Ben Finney <ben+python@benfinney.id.au> - 2016-04-30 12:49 +1000
                Re: What should Python apps do when asked to show help? Steven D'Aprano <steve@pearwood.info> - 2016-04-30 13:23 +1000
                Re: What should Python apps do when asked to show help? Ben Finney <ben+python@benfinney.id.au> - 2016-04-30 14:06 +1000
                Re: What should Python apps do when asked to show help? Random832 <random832@fastmail.com> - 2016-04-30 00:16 -0400
                Re: What should Python apps do when asked to show help? Rustom Mody <rustompmody@gmail.com> - 2016-04-29 21:34 -0700
                Re: What should Python apps do when asked to show help? Random832 <random832@fastmail.com> - 2016-04-30 01:20 -0400
                Re: What should Python apps do when asked to show help? cs@zip.com.au - 2016-05-01 09:51 +1000
                Re: What should Python apps do when asked to show help? Steven D'Aprano <steve@pearwood.info> - 2016-05-01 14:28 +1000
                Re: What should Python apps do when asked to show help? Random832 <random832@fastmail.com> - 2016-04-30 20:41 -0400
                Re: What should Python apps do when asked to show help? Grant Edwards <grant.b.edwards@gmail.com> - 2016-05-01 02:30 +0000
                Re: What should Python apps do when asked to show help? Random832 <random832@fastmail.com> - 2016-04-30 23:46 -0400

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