[Python-3000] Making more effective use of slice objects in Py3k (original) (raw)

Josiah Carlson jcarlson at uci.edu
Mon Aug 28 04:20:42 CEST 2006

"Delaney, Timothy (Tim)" <tdelaney at avaya.com> wrote:

Jim Jewett wrote: > On 8/27/06, Delaney, Timothy (Tim) <tdelaney at avaya.com> wrote: >> Jim Jewett wrote: > >>> s[start:stop].find(prefix) > >> No matter what, I really think the obj[start:stop:step] >> syntax needs to be consistent in its behaviour - either >> returning a copy or a view - > > Does it still matter if we're looking only at immutable sequences, > such as text? Actually, yes. I think it should be an explicit operation to say "I'm taking a small view of this large string, which will result in the large string existing until the view goes away". Currently the way to do that is to have a method. I'm simply proposing that we reserve syntax that is currently not used to prevent it from being used for another, less appropriate usage. It may never be used at all.

In what I have been attempting to propose, no text methods would ever return a view. If one wants a view of text, one needs to manually construct the view via 'view = textview(st, start, stop)' or some equivalent spelling. After that, any operations on a view returns views (with a few exceptions, like steps != 1).

The seemingly proposed textobj(start:stop) returning a view is not terribly intuitive, as () and [] aren't so terribly different from each other to not confuse someone initially. Never mind that it would be a syntax addition for the equivalent of a small subset of operations on currently existing objects.

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