[Python-3000] bytes and dicts (was: PEP 3137: Immutable Bytesand Mutable Buffer) (original) (raw)

Phillip J. Eby pje at telecommunity.com
Sat Sep 29 18:01:00 CEST 2007

At 10:26 AM 9/29/2007 -0500, Michael Urman wrote:

[Sending direct because this is just a thanks and some idea fodder, but feel free to return this to the list]

On 9/29/07, Phillip J. Eby <pje at telecommunity.com> wrote: > can both be constants, a simple list.index() test could now raise a > TypeError, as could "item in list". Good point - I keep missing the forest for the trees. This isn't just a matter of dicts; any collection type can be susceptible. Thanks for this reminder. I'm torn on your idea of making a read vs readinto separation of files. If this works by, e.g., raising IOError on attempt to use the wrong one, the use case you proposed will be filtering out a ton of expected exceptions, but it's easy to understand the behavior. If it works by removing the wrong method from the object, then we've got two different file-like object types returned from the same function based on the value of an argument (but a better LBYL check available). Of course since we currently have two different types returned from a method based on a value passed to its constructor, this may be no worse. I'm not sure which way makes it easier to add new file-like-objects, either; they'll have the same problems.

They'll have the same problems anyway. In fact, having different methods will simply force people creating such objects to decide what they're really trying to do.

More information about the Python-3000 mailing list