string formatting

[Raymond Hettinger]

> Which is the preferred way of string formatting?
>
> (1) "the %s is %s" % ('sky', 'blue')
>
> (2) "the {0} is {1}".format('sky', 'blue')
>
> (3) "the {} is {}".format('sky', 'blue')
>
> As I know (1) is old style. (2) and (3) are new but (3) is only
> supported from Python 2.7+.
>
> Which one should be used?


Sometimes, I use both ;-)
That can save you from ugly escapes such as %%s or {{0}}.

Here's an example from the standard library:
http://hg.python.org/cpython/file/7254c03b7180/Lib/collections.py#l235

Note the template has both {typename} formatting for the first pass
and %r style formatting in the generated code.

Raymond

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