[Python-3000] struni and the Apple four-character-codes (original) (raw)

Jeffrey Yasskin jyasskin at gmail.com
Wed Jul 25 07🔞00 CEST 2007

I'm looking through a couple of the OS X tests and have run into the question of what to do with four-character codes. (For those of you who are unfamiliar with these, Apple, around the dawn of time, decided that C constants like 'TEXT' (yes, those are single quotes) would compile to the uint32_t 0x54455854 (or maybe the other-endian version of that) so they could use these as cheap-but-readable type identifiers.) In Python 2, these are represented as 'str' instances, which PyMac_GetOSType() in Python/mactoolboxglue.c converts to the native int format. For Python 3, right now they're str8's, but str8 is theoretically supposed to go away. Because they're binary constants displayed as ASCII, not unicode text, I initially thought that 'bytes' was the appropriate type. Unfortunately, bytes is mutable, and I think it makes sense to hash these constants (and some code in aepack.py does).

So, I'm stuck and wanted to ask the list for input. I see 5 options:

  1. Make these str instances so they're immutable and just rely on convention and runtime errors to keep them in ascii.
  2. Make them bytes, and cast them to something else when you want to make them keys in a dict.
  3. Keep them str8 and give up on getting rid of it.
  4. Make bytes immutable, add a 'buffer' type which acts like the current bytes type, and make these codes instances of bytes. [probably impossible this late in the game]
  5. Make a new hashable class for these codes which converts them to and from ints and bytes and becomes the general argument type for the apple platform interface. [Cleanest, but lots of work that I'm not volunteering to do]

Thoughts? Jeffrey

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