From: Mark Hahn <mchahn@...>
Date: 2001-11-26T02:43:18+09:00
Subject: [ruby-talk:26462] Re: ++operator and sorted hashes


> In c++ maps are sorted

I have noticed before that Ruby is lacking a sorted map and a sorted set.  I
miss the sortedTreeMap class from Java, which is a good general
implementation of sorted maps.  I have an interesting algorithm for
automatically balanced trees that I have been considering implementing in
Ruby.

-----Original Message-----
From: Jakub Travnik [mailto:j.travnik@sh.cvut.cz]
Sent: Sunday, November 25, 2001 6:45 AM
To: ruby-talk ML; undisclosed-recipients:
Subject: [ruby-talk:26450] Re: ++operator and sorted hashes


Willi Kappler wrote:

> Hi list,
>
> I'm new to ruby ( using 1.6.5 ) and comming from c++. The language is
really great
> and easy to learn. But there are some things that would be fine
> if they were implemented:
>
> Is there a certain reason why the ++operator is not implemented ?
> In c/c++: a=5; a++;
> In ruby: a=5; a+=1


In Ruby everthing is object,
a++ means add one in C.
What this should mean for String? for Regexp? for Your own class?
It does not have usefull object semantic.

However a+=something is ok:
a=10;a+=1

a='Hello'; a+=' world'

a=MyClass.new; a+=MyClass.new
(if MyClass have instance method + defined)


> An other really usefull object is hash ( map in c++ stl )
> In c++ maps are sorted, in ruby there is a sort function, but it
> returns an array. I thought that c++ uses sorted maps for speedup
> reasons, so there must be an other reason why ruby doesn't sort them ?


It is a implementation reason.
there are some links that might explain more about hash tables:
http://www.nist.gov/dads/HTML/hashtab.html
http://www.wikipedia.com/wiki/Hash_table


Jakub Travnik
jabber://jtra@jabber.com
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