Background on why Ruby doesn't support ++

[Adam Lauper]

Hi All,

I'm a big Ruby fan and I'm not trying to complain.

I'm just curious as to why Ruby doesn't support the ++ or -- operators.
Is there some syntactical ambiguity that's associated with it or
something.

Anyone know the history on this deliberate omission?

Thanks!

Adam

 

[Shajith Chacko]

Anyone know the history on this deliberate omission?

Matz addressed this in ruby-talk 2710:

http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/2710

HTH!
Shajith

 

[Robert Klemme]

Matz addressed this in ruby-talk 2710:

http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/2710

Basically it is a consequence of the decision to make integers
immutable which makes assignment necessary for a variable which is
incremented. I guess Matz wanted to make this explicit, hence "+="
Co.

Otherwise you need a counter class, e.g.

Counter = Struct.new :value do
def initialize(x = 0)
self.value = x
end

def plusplus
self.value += 1
end

alias incr plusplus

def minusminus
self.value += 1
end

alias decr minusminus
end



Kind regards

robert

 

[Robert Dober]

Basically it is a consequence of the decision to make integers
immutable which makes assignment necessary for a variable which is
incremented.

Makes sense, though strictly speaking x++ could be syntactic sugar for
x+=3D1 or x =3Dx +1
but this would probably be very confusing for many folks for the very
reason you gave.
Cheers
Robert
--=20
module Kernel
alias_method :=EB, :lambda
end

 

[Mark Thomas]

Don't forget there's already

x.next

although there is not the orthogonal x.prev, which seems like the
Principle of Most Surprise in effect . One way to rectify that is
to open up Integer yourself:

class Integer
def prev
self - 1
end
end

 

[Robert Klemme]

Don't forget there's already

x.next

although there is not the orthogonal x.prev, which seems like the
Principle of Most Surprise in effect . One way to rectify that is
to open up Integer yourself:

class Integer
=A0def prev
=A0 =A0self - 1
=A0end
end

There is also #succ and #pred. But this is not the point: all of them
work by returning _a different object_. You can easily verify by
looking at the result's #object_id. Operators ++ and -- in C++ on the
other hand change the object (int, long etc.) itself. The difference
is whether you will have aliasing or not.

Kind regards

robert

--=20
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/