From: Lars Christensen <larsch@...>
Date: 2001-08-24T05:38:25+09:00
Subject: [ruby-talk:20207] Re: ++ Operator

On Fri, 24 Aug 2001, Yukihiro Matsumoto wrote:

> "++" in C/C++ is fundamentally an assignment, or in other words, an
> operation on variable not object, so that it would not fit well in
> object-oriented model.  Try "i+=1" instead.

I don't think of ++ as an assignment, as much as a "modification" to what
it is used one. Having written much C and C++ code, the +, += and
"missing" ++ operators semantics in Ruby are hard for me to accept.

This is how I would have done it:

---

+= should be a method, not an operator. It modifies the object using
addition or appending. Lot of methods in ruby already modify their object.

    a = b = 2
    a += 2
    a  # => 4
    b  # => 4

+ is a method defined in terms of +=, so that "a = b + c" is equivalent to
"a = b.dup; a += c". In case of string appending or even Numeric addition,
a more efficient implementation can be made by allowing + to be overloaded
(like C++).

++a and a++ are also operators perhaps mapped to methods such as
Numeric#++ and Numeric#++@, and having C semantics. They also modify the
object (and return the value after or before).

    a = b = 3
    a++
    a   #=> 4
    b   #=> 4

The same for --a and a--.

---

Note that a += 1 today involves making duplicate of A, adding 1 to it and
return a reference to the new object, where as a++ would map directly to
the same instruction in C. No objects copied, created or deleted!

a++ is "the efficient way" in my mind. Making "a++" an alias for "a += 1"
or "a = a + 1"  wouldn't make it any better. It has to be the operation
that increases the referenced object (Numeric) by one.

This may be a drastic change, but I would vote for it.  This would be much
more natural in my C mind than current Ruby. Methods that modify the state
of the object are even common in Ruby and are indeed "object oriented".
Avoiding them is "functional thinking" IMO.

-- 
Lars Christensen, larsch@cs.auc.dk