[Python-Dev] transform() and untransform() methods, and the codec registry (original) (raw)

Guido van Rossum guido at python.org
Fri Dec 10 18:54:56 CET 2010

On Thu, Dec 9, 2010 at 11:17 AM, Antoine Pitrou <solipsis at pitrou.net> wrote:

On Thu, 9 Dec 2010 13:55:08 -0500 Alexander Belopolsky <alexander.belopolsky at gmail.com> wrote:

On Thu, Dec 9, 2010 at 1:42 PM, Guido van Rossum <guido at python.org> wrote: .. > string-string transforms use the same namespace even though the > typical transform only supports one or the other. E.g. IMO all of the > following should raise LookupError: > >>>> b'abc'.transform('rot13') > Traceback (most recent call last): > .. >    return (input.translate(rot13map), len(input)) > TypeError: expected an object with the buffer interface

This is actually very misleading because >>> 'abc'.transform('rot13') 'nop' works even though 'abc' is not "an object with the buffer interface". Agreed. It was already pointed out in the parent thread. I would say my opinion on keeping transform()/untransform() is +0 if these error messages (and preferably the exception type as well) get improved. Otherwise we'd better revert them and add a more polished version in 3.3.

Let me change my opinion then and say that I'm -1 on keeping the confusing situation. It can be fixed either by postponing transform() until 3.3 or by fixing the error checking and namespace issue.

Sorry about the reversal of pronouncements, but my original approval was very weak indeed and mostly driven by "stick to status quo unless there's a serious problem". The followup made it clear that the errors and namespace issue are more seriously than I estimated at first.

-- --Guido van Rossum (python.org/~guido)

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