From: Greg McIntyre <greg@...>
Date: 2003-11-20T07:42:16+09:00
Subject: ! usage

Michael Neumann <uu9r@stud.uni-karlsruhe.de> wrote:
> My understanding is, that "delete" is a destructive word itself, so it
> doesn't need to be marked explicitly as "dangerous". If you need a
> non-destructive delete_if version, better use the Enumerable#reject
> method, which IMHO describes better it's internal sematics. Here, it's
> destructive counterpart, reject! exists.
> 
> Your suggestion is that delete_if does not delete anything (it creates
> a new array), where delete_if! would. Principle of Least Surprise? Not
> for me!

That isn't my suggestion, but we do have conflicting POLS. :)

My suggestion is that one _should_ be able to do this:

  a = [1,2,3]
  a.join!

with only Array#join defined.

Basically I see inconsistency. Personally I'd expect delete_if to have
a ! because it modifies the receiver like map! and reject!, regardless
of whether it's clear. Clarity is not just subjective, it's highly
subjective! :)

So _is_ there a rule or mnemonic for ! usage in method names, other than
"danger"? Is there a technical rule? In the standard library it seems to
be that ! is used for in-place transformations to the same class; is
that it?

-- 
Greg McIntyre ======[ greg@puyo.cjb.net ]===[ http://puyo.cjb.net ]===