From: "David A. Black" <dblack@...>
Date: 2005-10-08T07:53:04+09:00
Subject: Re: select! not present but reject! is

Hi --

On Sat, 8 Oct 2005, Rob Rypka wrote:

> On 10/7/05, Mark Hubbart <discordantus@gmail.com> wrote:
>> Also, I'm not really advocating any action here. I'm just suggesting
>> that it would be a little weird for "select!" to be the exact opposite
>> of "reject!", since the Ruby definitions wouldn't stand up to the
>> English ones.
>
> select and reject (without the exclamation marks) are Ruby opposites,
> though.  Nobody seems opposed to that.

I hadn't thought we were talking about them.  They seem OK to me,
though I could imagine reject actually being an in-place operation
even without the !.

> If I had two methods, Array#foo and Array#foo!, I would expect the
> definition of foo! to be:
>
> "Same as Array#foo, but modifies the receiver in place."

See below about !, but also: I question what "select a subarray from
an array, in place" means.  It sounds to me like the selected subarray
is *removed* from the array.  Replacing the array with the selected
subarray seems to me to be a second transaction, not a select
operation per se.

> Sometimes, the above leads to another (near) synonym (like delete_if
> and reject!), but the  The return value should be the receiver,
> instead of a new array.   To me, foo! doesn't mean finding a new
> meaning of the foo operation in a way that would be destructive, it
> means immediacy to the receiver (which in turn implies destruction).
> "Select these elements, but alter your contents and return yourself,
> instead of someone new."

The ! doesn't mean that a method modifies the receiver in place,
though, but rather that this is a "dangerous" version of the method
and should be used carefully.  The "danger" often has to do with
in-place change, but ! itself doesn't mean that.


David

-- 
David A. Black
dblack@wobblini.net