string formatting

[Chris Angelico]

On Wed, May 11, 2011 at 12:15 AM, Web Dreamer <webdreamer at nospam.fr> wrote:
> I was unsure of the difference between deprecated and obsolete.
>
> So now, if I understand well, obsolete comes before deprecated, such that if
> a feature is obsolete it will be deprecated in an unknown future, after
> which it will be removed once it has been deprecated (a certain time after
> it was rendered obsolete)?
> (might need an aspirin to read that one :-) )
>
> So If I'm right, old string formatting "could" one day be deprecated but it
> is not yet?

I wouldn't say that obsolete features "will be" deprecated. That
expression makes little sense (I know, for I have seen it in eBay's
API documentation, and it did not fill me with joy). Deprecation is
(usually) a formal procedure that clearly states that a feature should
not be used. It may be accompanied by a strict cutoff ("will be
removed in version X"), or just left vague, but linting tools can
identify all use of deprecated features.

Obsolete, however, is simply a description. Sopwith Camels were
obsolete in the second world war, and VHS has been obsoleted by
optical disc media. However, if you wish to fly a Camel or play a VHS,
nothing's stopping you. The sky will still accept your Camel, and your
VHS player will still talk to your television. (The analogy breaks
down a bit in that your obsolete VHS player may be using a deprecated
cabling style, but it's coax that's deprecated, not VHS.) There's no
"projected end date" for them.

Generally, a feature is obsolete before it's deprecated, but
technically that's not a requirement, and API designers can sometimes
be quite arbitrary. On the other hand, obsolescence is quite informal,
and people can disagree about whether or not something is. (Hi Ken,
your continued use of inches is noted. Thank you.)

Chris Angelico