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Re: [Python-ideas] string.format() default variable assignment

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On Sat, Mar 2, 2013 at 3:55 AM, 김용빈 <kybinz@gmail.com> wrote:
> why we bother with '{variable}'.format(variable=variable) ?
> can we just '{variable}.format()' ?
>
> if variable is exist, then assign it.
> if variable is not exist, then raise error
>
> I am not language expert. so sorry if this is not a good idea, or already
> discussed.

You're asking for a facility whereby variables magically get pulled
from the caller's scope. Let me put it to you another way:

def func1():
   return foo + " world"

def func2():
    foo = "Hello"
    print("func1 returns: "+func1())

func2()

Will this work? If not, why not?

There are ways around this; you can, for instance, pass locals() to format():
'{variable}'.format(**locals())

But this is massive overkill and can unexpectedly expose a whole lot
more than you wanted (an issue if you accept a format string from an
untrusted source). Generally, it's best to be explicit. You can avoid
repeating the name so much by using positional parameters instead:

'{0}'.format(variable)

Of course, this has its own considerations. But at least it isn't magical. :)

ChrisA

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Re: [Python-ideas] string.format() default variable assignment Chris Angelico <rosuav@gmail.com> - 2013-03-02 04:07 +1100
  Re: [Python-ideas] string.format() default variable assignment Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-03-02 01:43 +0000
    Re: [Python-ideas] string.format() default variable assignment Chris Angelico <rosuav@gmail.com> - 2013-03-02 14:54 +1100
    Re: [Python-ideas] string.format() default variable assignment Devin Jeanpierre <jeanpierreda@gmail.com> - 2013-03-02 01:09 -0500
    Re: [Python-ideas] string.format() default variable assignment Chris Angelico <rosuav@gmail.com> - 2013-03-02 17:54 +1100
    Re: [Python-ideas] string.format() default variable assignment James Griffin <jmz.griffin@kode5.net> - 2013-03-02 08:06 +0000
    Re: [Python-ideas] string.format() default variable assignment Devin Jeanpierre <jeanpierreda@gmail.com> - 2013-03-02 09:53 -0500
      Re: [Python-ideas] string.format() default variable assignment Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-03-03 00:27 +0000
        Re: [Python-ideas] string.format() default variable assignment Roy Smith <roy@panix.com> - 2013-03-02 19:42 -0500
          Re: [Python-ideas] string.format() default variable assignment Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-03-03 03:19 +0000
        Re: [Python-ideas] string.format() default variable assignment David Robinow <drobinow@gmail.com> - 2013-03-02 21:11 -0500
          Re: [Python-ideas] string.format() default variable assignment Roy Smith <roy@panix.com> - 2013-03-02 21:15 -0500
            Re: [Python-ideas] string.format() default variable assignment David Robinow <drobinow@gmail.com> - 2013-03-02 22:01 -0500
            Re: [Python-ideas] string.format() default variable assignment Chris Angelico <rosuav@gmail.com> - 2013-03-03 14:06 +1100
            Re: [Python-ideas] string.format() default variable assignment David Robinow <drobinow@gmail.com> - 2013-03-02 22:18 -0500
            Re: [Python-ideas] string.format() default variable assignment Chris Angelico <rosuav@gmail.com> - 2013-03-03 14:46 +1100
          Re: [Python-ideas] string.format() default variable assignment Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-03-03 03:21 +0000
            Re: [Python-ideas] string.format() default variable assignment Devin Jeanpierre <jeanpierreda@gmail.com> - 2013-03-02 23:00 -0500
              Re: [Python-ideas] string.format() default variable assignment Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-03-03 10:33 +0000
            Re: [Python-ideas] string.format() default variable assignment Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-03-03 09:51 +0000
            Re: [Python-ideas] string.format() default variable assignment David Robinow <drobinow@gmail.com> - 2013-03-04 11:09 -0500
              Re: [Python-ideas] string.format() default variable assignment Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-03-05 02:42 +0000
                Re: [Python-ideas] string.format() default variable assignment Chris Angelico <rosuav@gmail.com> - 2013-03-05 13:54 +1100
                Re: [Python-ideas] string.format() default variable assignment Gene Heskett <gheskett@wdtv.com> - 2013-03-04 23:01 -0500
                Re: [Python-ideas] string.format() default variable assignment James Griffin <jmz@kontrol.kode5.net> - 2013-03-05 08:16 +0000
                Re: [Python-ideas] string.format() default variable assignment Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-03-05 11:35 +0000
            Re: [Python-ideas] string.format() default variable assignment David Robinow <drobinow@gmail.com> - 2013-03-04 11:15 -0500
            Re: [Python-ideas] string.format() default variable assignment Dave Angel <davea@davea.name> - 2013-03-04 13:31 -0500
    Re: [Python-ideas] string.format() default variable assignment Tim Golden <mail@timgolden.me.uk> - 2013-03-02 15:01 +0000
    Re: [Python-ideas] string.format() default variable assignment Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-03-02 12:31 -0500
    good mail readers  [was Re: [Python-ideas] string.format() default variable assignment] Ethan Furman <ethan@stoneleaf.us> - 2013-03-02 11:59 -0800

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