[Python-Dev] [Python-checkins] cpython (3.2): Issue #14123: Explicitly mention that old style % string formatting has caveats (original) (raw)

Terry Reedy tjreedy at udel.edu
Sun Feb 26 20:22:56 CET 2012

On 2/26/2012 1:50 PM, martin at v.loewis.de wrote:

Zitat von Eli Bendersky <eliben at gmail.com>:

- The formatting operations described here are obsolete and may go away in future - versions of Python. Use the new :ref:string-formatting in new code. + The formatting operations described here are modelled on C's printf() + syntax. They only support formatting of certain builtin types. The + use of a binary operator means that care may be needed in order to + format tuples and dictionaries correctly. As the new + :ref:string-formatting syntax is more flexible and handles tuples and + dictionaries naturally, it is recommended for new code. However, there + are no current plans to deprecate printf-style formatting. Please consider just deleting the last sentence. Documentation is meant for users (often new users) and not core devs. As such, I just don't see what it adds. If the aim to to document this intent somewhere, a PEP would be a better place than the formal documentation. I'd rather leave the last sentence, and delete the penultimate sentence. The last sentence is useful information to the end user ("we will not deprecate printf-style formatting, so there is no need to change existing code"). I'd drop the penultimate sentence because there is no consensus that it is a useful recommendation (and it is certainly not a statement of fact).

I agree that the 'recommendation' is subjective, even though I strongly agree with it for new Python programmers who are not already familiar with printf style formatting. However, that sort of nuanced recommendation goes better in a HowTo. Statements about non-deprecation are also out of place as that is the default. So I agree with both of you. Let us drop both of the last two sentences. Then we can all be happy.

There is a difference between 'There are no current plans to ...' and 'We will never ...'. However, '...' should not be discussed or even proposed or even mentioned until there is a bug-free automatic converter. I think the recent rehashing was mostly a needless irritation except as it prompted a doc update.

Terry Jan Reedy

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