From: Gavin Sinclair <gsinclair@...>
Date: 2002-12-09T19:08:43+09:00
Subject: Re: [YANQ] -yet another (ruby) newbie question -string#concat

From: "Pe�a, Botp" <botp@delmonte-phil.com>


>
> >As for having all destructive/modifying methods use !: we'd end up
> >with an awful lot of !'s in our code :-)
> >
> >  a =3D [1,2,3,4]
> >  a.push!(5)     # and a.push(5) would create a dup of a???
> >  a[-1]! =3D 6     # as in:  a.[]=3D!(-1,6)
> >  a.delete_if! {|x| x =3D=3D 3}
> >
> >etc., etc....
>
> They are indeed too many. And "!" makes method names _ugly_. So basically,
> the question is how to recognize destructive methods (since I guess we
> cannot live/trust with "!" alone).

No, they are _beautiful_.  Repeat after me: _beautiful_ ;)


> >
> >There's a lot of previous discussion on this (the general ! question,
> >not concat specifically).  I searched for "destructive modify
> >receiver" on ruby-talk and hit a few such threads.
>
> I would have prefered that there be NO destructive methods.
> So using your examples above, I would rewrite them as:
>
>   a = [1,2,3,4]
>   a = a.push(5)
>   a = (a[-1] = 6)  #errs since []= does not return array
>   a = a.delete_if! {|x| x == 3}
>
> and, I'm actually doing ruby coding like this now (pls don't laugh :-):

I can't help laughing, I'm afraid, but it's with the greatest of affection for
yourself and all the useful questions you ask!


> a = [1,2,3,4]
> b = a.dup #save a
> a = a.push(5).delete_if{|x| x==2} # modify a anytime
>
> p "a now is ",a
> p "a originally was ",b
>
> Imho, the <receiver> = <receiver>.method.... is more explicit and therefore
> less confusing. True, it needs more typing, but that is the price I have to
> pay of being very explicit (and less questions for me).

There's nothing really confusing about objects being modified.  All data can be
modified, so why not the data in objects?  I think you need to treat your
symptoms like a fear of spiders: confront your fear, modify every object in
sight until you are used to it ;)   (just kidding, of course)


> Or maybe, how about a ruby directive/option that disables methods fr being
> destructive (so that nubies like me would have a playing field)?

Now that's just being ridiculous! :D

Anyway, you have two options at your disposal:
 - irb is an *excellent* playing field
 - freeze every object you create, then you can't modifiy them!

Cheers,
Gavin