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From: Ben Finney <ben+python@benfinney.id.au>
Newsgroups: comp.lang.python
Subject: Re: new string formatting with local variables
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Date: Tue, 07 Jun 2011 17:47:58 +1000
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Steven D'Aprano <steve+comp.lang.python@pearwood.info> writes:

> On Tue, 07 Jun 2011 10:11:01 +1000, Ben Finney wrote:
>
> > I tend to use ‘u"foo {bar} baz".format(**vars())’, since ‘vars’ can
> > also take the namespace of an object. I only need to remember one
> > “give me the namespace” function for formatting.
[…]

>
> It's a code smell. Why is this code messing with locals() instead of 
> using names explicitly? Is it possible that this code will attempt to 
> modify locals()? I need to look twice to be sure its safe. Why do you 
> need to pass *all* of the locals if only two names are used?

The names are explicit; they're in the format string. It's because I
don't want to repeat the names several times that I'm making use of the
dictionary provided by ‘vars()’.

> Where possible, I'd rather be explicit about which names I want:
>
> solo = "Han Solo"
> jabba = "Jabba the Hutt"
>
> "{hero} was captured by {villain}.".format(hero=solo, villain=jabba)

See, repeating those name references makes *me* hinky. I used those
names because they refer to things I've already named.

-- 
 \        “The difference between religions and cults is determined by |
  `\                      how much real estate is owned.” —Frank Zappa |
_o__)                                                                  |
Ben Finney