[Python-Dev] PEP 355 status (original) (raw)

James Y Knight foom at fuhm.net
Thu Oct 26 09:00:57 CEST 2006

On Oct 25, 2006, at 10:48 PM, Talin wrote:

That's true of textual paths in general - i.e. even on unix, textual paths aren't guaranteed to be unique or exist.

Its been a while since I used classic MacOS - how do you handle things like configuration files with path names in them?

You aren't supposed to use paths at all. You're supposed to use an
Alias whenever you're doing long term storage of a reference to a
file. This allows the user to move the file around on the disk
without breaking the reference, which is nice. The alias is an opaque
datastructure which contains a bunch of redundant information used to
locate the file. In particular, both pathname and (volumeId, dirId,
name), as well as some other stuff like file size, etc. to help do
fuzzy matching if the original file can't be found via the obvious
locators. And for files on a file server, it also contains
information on how to reconnect to the server if necessary.

Much of the alias infrastructure carries over into OSX, although the
strictures against using paths have been somewhat watered down. At
least in OSX, you don't have the issue of the user renaming the boot
volume and thus breaking every path someone ill-advisedly stored
(since volume name was part of the path).

For an example of aliases in OSX, open a file in TextEdit, see that
it gets into the "recent items" menu. Now, move it somewhere else and
rename it, and notice that it's still accessible from the menu.
Seperately, try deleting the file and renaming another to the same
name. Notice that it also succeeds in referencing this new file.

Hm, how's this related to python? I'm not quite sure. :)

James

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