PyFormat – Practical examples of old and new style string formatting

Re:PyFormat – Practical examples of old and new style string... by quarktasche on Wednesday April 15, 2015 @06:06PM (#9384521)

Might not work in some special cases though. Try:

  def foo():
      a = 4
      def bar():
          print("a = {a}".format(**locals()))
      bar()
        
  foo()

which will raise a KeyError, while it will work fine if you add a

  print(a)

to the end of bar().

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Re:PyFormat – Practical examples of old and new style string... by fragmede on Wednesday April 15, 2015 @06:16PM (#9384588)

Actually, if you reference 'a' at all in bar, it will work:

    def foo():
        a = 4
        def bar():
            a
            print("a = {a}".format(**locals()))
        bar() 
    foo()

successfully prints

    a = 4

which is a bit confusing, but makes sense if you think about it.

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Re:PyFormat – Practical examples of old and new style string... by gcr on Wednesday April 15, 2015 @06:24PM (#9384634)

In this case, 'a' isn't a local variable binding though.

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Re:PyFormat – Practical examples of old and new style string... by pyre on Thursday April 16, 2015 @02:01AM (#9386110)

Right, but it's accessible in scope though. It's just a "gotcha" for that method that might be easy to overlook if you aren't paying attention (or if someone with less experience stumbles onto this 'trick' in production code).

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