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  On 06/14/2012 01:53 PM, Antoine Pitrou wrote:<br>

  <blockquote cite="mid:20120614225337.2b1fe5a9@pitrou.net"

   type="cite">

   <blockquote type="cite">

    <pre wrap="">* is_implemented : bool

  True if the parameter is implemented for use. Some platforms

  implement functions but can't support specific parameters

  (e.g. "mode" for ``os.mkdir``). Passing in an unimplemented

  parameter may result in the parameter being ignored,

  or in NotImplementedError being raised. It is intended that

  all conditions where ``is_implemented`` may be False be

  thoroughly documented.

</pre>

   </blockquote>

   <pre wrap="">

I don't understand what the purpose of is_implemented is, or how it is

supposed to be computed.</pre>

  </blockquote>

  <br>

  It's computed based on locally available functionality.&nbsp; Its purpose

  is to allow LBYL when using functionality that may not be available

  on all platforms.&nbsp; See issue 14626 for a specific use-case--which is

  why I pushed for this.<br>

  <br>

  When all the chips fall into place, I expect to have some code that

  looks like this:<br>

  <blockquote><tt>os.chown.__signature__.parameters['fd'].is_implemented

    = sysconfig.get_config_var('HAVE_FCHOWN')</tt><br>

  </blockquote>

  That's oversimplified (and almost certainly not spelled correctly)

  but you get the general idea.&nbsp; os.chown will soon sprout an "fd"

  parameter, but it will only work on platforms where we have

  fchown().&nbsp; Using it will result in a NotImplementedError.&nbsp; But some

  folks want to LBYL.<br>

  <br>

  <br>

  <i>/arry</i><br>

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