From: Hal Fulton <hal9000@...>
Date: 2003-08-27T05:52:06+09:00
Subject: Re: Array#uniq!

Mark Wilson wrote:
> The inspiration for these thoughts is the implementation in the set 
> class, where the default is to return the object whether or not the 
> method modified the contents of the container. If one wants to know 
> whether the modification occurred, one calls the method with a question 
> mark appended.
> 
> For example Set#add(object) will add the object if it does not exist in 
> the set and return the modified set. If the object is in the set, it is 
> not added and the set is returned. Set#add?(object) will add the object 
> if not already present and return 'nil' if the object is already present.

[snippage]

> I don't know whether or how these method returns should be changed, but 
> I do think the topic is worth further thought and discussion.

I've thought about these issues, too... I usd to be bitten frequently
by the nil-return bug^H^H^H feature. But then I just fell out of the
habit of chaining certain methods.

I never use the fact that they return nil.

On the other hand, the add? method seems a little unintuitive to me...
in principle I like it OK, but it is a little unusual that a ?-method
changes its receiver. I don't know anywhere else that happens.

I once suggested as a joke four other suffixes: !!, ??, ?!, and !?.
But the last of these is looking slightly more serious and less of a
joke now. But no, I'm not seriously proposing it. Who would use a
language feature like !? on a method name?

Cheers,
Hal