From: Christophe Grandsire <christophe.grandsire@...>
Date: 2005-10-18T21:37:56+09:00
Subject: Re: A couple of questions/statements from a Ruby neohacker

Selon Robert Klemme <bob.news@gmx.net>:

>
> I'm not so sure: the history of this list / ng has shown that this issue
> has irritated people over and over again.

And it has also shown that many people agree with the convention as I have
stated it. And from the mouth of the master himself (from:
http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/2331):

"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'."

As long as matz himself keeps with this convention (and he has shown no sign of
wanting to change it, especially since it would cover Ruby with !'s - check the
rest of the that thread -), I don't think we should either. ! is *not* for
destructive methods. It's for methods that already exist in a non-bang form,
and which do something similar to them but in a dangerous way. There are plenty
of destructive methods that don't have a bang (because they don't have a
non-destructive version), and I don't believe it would be a gain to add a ! to
all of them, especially since it would in my opinion break the aesthetics of
Ruby.

  So the convention that was
> followed in implementing this might be a different one from the publicly
> observed one.  One reason for this might be that the term "dangerous" in
> this context is much broader and less precise than the term "destructive"
> (changing the receiver's state).  Also "dangerous" is very context
> sensitive (even IO#puts might be regarded as dangerous in certain
> situations) which adds to the difficulty.

But in this case it's simple: to get a !, a method has to have a counterpart
that does about the same work, and be more dangerous (destructive, unsafe,
etc...) than the other one.

  It might be an interesting
> philosophical debate which of the two conventions is more adhered to, as a
> convention is a social thing...
>

I believe the convention that bang methods always have a non-bang alternative,
and that destructive methods without a non-destructive alternative don't have
one, is pretty well followed.

I made a cursory look at about 4 years of the history of the Ruby-talk list, and
everything I read seems to indicate that the convention is pretty well followed.
In any case, I don't believe any other convention would be better. Just remember
that if you think of putting a ! on your method you need one without the bang.
If it doesn't make sense to have such an alternative, your method doesn't need
a bang.
--
Christophe Grandsire.

http://rainbow.conlang.free.fr

It takes a straight mind to create a twisted conlang.