[Python-ideas] String formatting
steve at pearwood.info
Sat Sep 28 14:32:46 CEST 2013
On Sat, Sep 28, 2013 at 01:53:37AM -0700, Ram Rachum wrote:
> Any reason why string formatting using % doesn't work when the list of
> arguments is in a list rather than a tuple?
Because it's not supposed to. It is part of the design of % that
arbitrary objects, including lists, require only a single % target:
py> L = list(range(8))
py> "Values: %s" % L
'Values: [0, 1, 2, 3, 4, 5, 6, 7]'
The deliberately single exception to that are tuples. This is
unavoidable, since there's otherwise no other way for a binary operator
like % to take arbitrary numbers of arguments.
Besides, even if this were a good idea, 20+ years of code that expects
lists to be treated as a single object for the purposes of % formatting
says we can't change it now.
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