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RE: Beginner question

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> From: steve+comp.lang.python@pearwood.info
> Subject: Re: Beginner question
> Date: Tue, 4 Jun 2013 12:35:59 +0000
> To: python-list@python.org
> 
> On Tue, 04 Jun 2013 14:23:39 +0300, Carlos Nepomuceno wrote:
> 
> > Started answering... now I'm asking! lol
> > 
> > I've tried to use dict() to create a dictionary to use like the switch
> > statement providing variable names instead of literals, such as:
> > 
> >>>> a='A'
> >>>> b='B'
> >>>> {a:0,b:1}    #here the variables are resolved
> > {'A': 0, 'B': 1}
> > 
> > That's ok! But if I use dict() declaration:
> > 
> >>>> dict(a=0,b=1)
> > {'a': 0, 'b': 1}    #here variable names are taken as literals
> > 
> > What's going on? Is there a way to make dict() to resolve the variables?
> 
> 
> This is by design. You're calling a function, dict(), and like all 
> functions, code like:
> 
> func(name=value)
> 
> provides a *keyword argument*, where the argument is called "name" and 
> the argument's value is as given. dict is no different from any other 
> function, it has no superpowers, keyword arguments are still keyword 
> arguments.
> 
> In this case, there is no simple way to use the dict() function[1] the 
> way you want. You could build up a string and then call eval():
> 
> s = "dict(%s=0, %s=1)" % (a, b)
> d = eval(s)
> 
> but that's slow and inconvenient and dangerous if your data is untrusted.
> 
> So in this specific case, you should stick to the {} method.
> 
> 
> 
> [1] Technically it's a type, not a function, but the difference makes no 
> difference here.
> 
> -- 
> Steven

It's superclear now! You're an excelent teacher!

Can you explain me the difference of the type and function you've just mentioned?

 		 	   		  

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Beginner question eschneider92@comcast.net - 2013-06-03 20:39 -0700
  RE: Beginner question Carlos Nepomuceno <carlosnepomuceno@outlook.com> - 2013-06-04 09:46 +0300
    Re: Beginner question John Ladasky <john_ladasky@sbcglobal.net> - 2013-06-04 00:53 -0700
      RE: Beginner question Carlos Nepomuceno <carlosnepomuceno@outlook.com> - 2013-06-04 11:17 +0300
  Re: Beginner question Anssi Saari <as@sci.fi> - 2013-06-04 10:45 +0300
    Re: Beginner question John Ladasky <john_ladasky@sbcglobal.net> - 2013-06-04 00:57 -0700
      Re: Beginner question Chris Angelico <rosuav@gmail.com> - 2013-06-04 18:24 +1000
      Re: Beginner question Peter Otten <__peter__@web.de> - 2013-06-04 11:23 +0200
      RE: Beginner question Carlos Nepomuceno <carlosnepomuceno@outlook.com> - 2013-06-04 14:23 +0300
        Re: Beginner question Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-04 12:35 +0000
          RE: Beginner question Carlos Nepomuceno <carlosnepomuceno@outlook.com> - 2013-06-04 15:51 +0300
            Re: Beginner question Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-07 02:21 +0000
      RE: Beginner question Fábio Santos <fabiosantosart@gmail.com> - 2013-06-04 12:34 +0100
      RE: Beginner question Carlos Nepomuceno <carlosnepomuceno@outlook.com> - 2013-06-04 14:53 +0300
        Re: Beginner question Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-04 12:25 +0000
          RE: Beginner question Carlos Nepomuceno <carlosnepomuceno@outlook.com> - 2013-06-04 15:37 +0300
          RE: Beginner question Fábio Santos <fabiosantosart@gmail.com> - 2013-06-04 13:47 +0100
      RE: Beginner question Fábio Santos <fabiosantosart@gmail.com> - 2013-06-04 13:15 +0100
      Re: Beginner question Mitya Sirenef <msirenef@lightbird.net> - 2013-06-04 13:16 -0400
  Re: Beginner question Larry Hudson <orgnut@yahoo.com> - 2013-06-04 02:13 -0700
    Re: Beginner question Roy Smith <roy@panix.com> - 2013-06-04 09:16 -0400
  Re: Beginner question Joshua Landau <joshua.landau.ws@gmail.com> - 2013-06-04 20:43 +0100
  Re: Beginner question eschneider92@comcast.net - 2013-06-05 20:42 -0700

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