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Date: Wed, 9 Jun 2021 00:01:54 +0100
From: Lancelot SIX <lsix@lancelotsix.com>
To: Simon Marchi <simon.marchi@polymtl.ca>
Cc: gdb-patches@sourceware.org
Subject: Re: [PATCH] Use is/is not to check for None in python.
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On Tue, Jun 08, 2021 at 12:25:37PM -0400, Simon Marchi wrote:
> On 2021-06-07 9:12 p.m., Mike Frysinger via Gdb-patches wrote:
> > On 07 Jun 2021 23:50, Lancelot SIX via Gdb-patches wrote:
> >> While reviewing a patch sent to the mailing list, I noticed there are few
> >> places where python code checks if a variable is 'None' or not by using the
> >> comparison operators '==' and '!='.  PEP8[1], which is used as coding standard
> >> in GDB coding standards, recommends using 'is' / 'is not' when comparing to a
> >> singleton such as 'None'.
> > 
> > this is correct, so all the changes look fine.  but i wonder if we couldn't
> > make many more pythonic by treating them as bools.  for example:
> 
> The patch LGTM but I also agree with Mike.  So Lancelot, if you want to
> merge it as-is, that's fine.  If you want to update it as suggested by
> Mike, that's fine too.
> 
> Simon
> 

Hi,

Thanks.

I have pushd the patch with minor modifications for the case Mike
pointed out.

After looking again, the pattern was:

    fname = str(self.fobj.function())
	  if fname is None or fname == "":
		    return None

but in this situation fname can not be None.  Worst case scenario, if
`self.fobj.function()` returns None, then `fname == 'None'`, so the
`is None` check is useless anyway.

For the rest, of the changes, I kept 'is None' / 'is not None'.

Lancelot.