From: Rob Rypka <rascal1182@...>
Date: 2005-10-08T09:25:31+09:00
Subject: Re: select! not present but reject! is

You had to reply, didn't you...

On 10/7/05, David A. Black <dblack@wobblini.net> wrote:
> 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 !.

I had tried (and failed) to make this point earlier.

> 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.

I stand (somewhat) corrected.  I had assumed some things based on
Pickaxe and my own delusional perspective into this world.

Before now, I had never been able to find information on the bang,
because I hadn't yet reduced my search results to replies from Matz. 
Here's the relevant quote from [ruby-talk:02331]:

"Unlike Scheme, not all change-in-place functions are named with
exclamation mark.  In Ruby, exclamation mark means `MORE dangerous',
or `may cause surprise' than non-bang counterpart, i.g. in-place
modification by `gsub!' may let you surprise, comparing copying
`gsub'."

I'm not trying to be mean by nit-picking a non-native speaker's
English, I'd like some clarification.  I knew that methods existed
that modified the object without !, but their names were pretty clear
(e.g., delete_if).  I thought the ! was there to imply modification of
the receiver, which could lead to unexpected results if used on a
function argument.

Are there any ! methods that don't modify the receiver?  Are there any
! methods that do not have normal "non-dangerous" counterparts?

I can't think of anything that would not modify the object, but be
considered "dangerous," unless it's going to cause your sysadmin to
come to your office and beat you with a shovel.

Then again, the proposed select! seems to have caused you surprise, so
I think the name still fits :-)

I think select! is the right name for a proposed companion to reject!,
but others don't, so I'm open.  It's funny how I seem to argue most
about things that don't really matter to me (like the name of this
method).

--
Rob