[Python-3000] Immutable bytes type and dbm modules (original) (raw)

Jim Jewett jimjjewett at gmail.com
Tue Aug 7 17:56:49 CEST 2007

On 8/7/07, Guido van Rossum <guido at python.org> wrote:

On 8/7/07, Nick Coghlan <ncoghlan at gmail.com> wrote: > This would mean that the Unicode type would acquire all of the ambiquity > currently associated with the 8-bit str type: does it contain actual > text, or does it contain arbitrary latin-1 decoded binary data?

...

> A separate frozenbytes type (with the bytes API instead of the string > API) would solve the problem far more cleanly.

But at a cost: an extra data type, more code to maintain, more docs to write, thicker books, etc.

I think that cost is already there, and we're making it even worse by trying to use the same name for two distinct concepts.

(1) A mutable buffer (2) A literal which isn't "characters"

Historically, most of the type(2) examples have just used ASCII (or at least Latin-1) for convenience, so that they look like characters. The actual requirements are on the bytes, though, so recoding them to a different output format is not OK.

Also note that for type(2), immutability is important, not just for efficiency, but conceptually. These are generally compile-time constants, and letting them change will lead to confusion. (Even letting them get replaced is confusing, but that sort of monkey-patching is sufficiently rare and obvious that it seems to work out OK today.)

-jJ

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