29 Nov
2022
29 Nov
'22
8:10 p.m.
It isn't possible to implement i++, but it is... kinda... possible to
implement ++i. Take a look at the following code. Just please don't use
it in production 😉
class IntContainer
 def initialize(value, origref=nil)
   @value = value
   @origref = origref
 end
 def +@
   case @origref
   when nil
     IntContainer.new(+@value, self)
   else
     @origref.value += 1
     @origref
   end
 end
 def -@
   case @origref
   when nil
     IntContainer.new(-@value, self)
   else
     @origref.value -= 1
     @origref
   end
 end
 attr_accessor :value
 def method_missing(meth, ...)
   IntContainer.new((a)value.send(meth, ...))
 end
 def inspect(...) = @value.inspect(...)
 def to_s(...) = @value.to_s(...)
end
int = IntContainer.new(5)
p int + 10
++int
p int
--int
p int
On 10/14/22 19:01, iloveruby wrote:
Is it posible define new method :++ to Integer class?
Thanks!
Enviado desde Proton Mail móvil
-------- Mensaje original --------
El 14 oct 2022 4:53, Martin DeMello < martindemello(a)gmail.com> escribió:
i++ works in C and similar languages because a variable is a
concrete object, representing a specific chunk of memory. i++
increments the contents of that chunk of memory.
in ruby, a variable is a transparent reference to an object, so
any operation on a variable is actually an operation on the object
it points to. i++ would mean "mutate the object i points to by
incrementing it by 1", and since numbers are immutable you cannot
do that. on the other hand, "i += 1" is just shorthand for "i =
i + 1", which means "point the variable i to a new object that is
1 more than the object it currently points to", which works fine
with ruby's semantics.
here's an illustration by contrast with strings, which do have
mutating methods:
irb(main):001:0> a = "hello"
=> "hello"
irb(main):002:0> b = a
=> "hello"
irb(main):003:0> a.upcase!
=> "HELLO"
irb(main):004:0> b
=> "HELLO"
irb(main):005:0> i = 1
=> 1
irb(main):006:0> j = i
=> 1
irb(main):007:0* i++ # <- what would you expect j to be after this?
martin
On Thu, Oct 13, 2022 at 7:40 PM Henrik P <henrik(a)simplemail.co.in>
wrote:
I found for a int the "++" operator doesn't work in ruby.
such as,
i=0
i++
not working. but instead it would write as:
i=0
i += 1
so "++" is not supported in ruby really? thanks
$ ruby -v
ruby 2.6.3p62 (2019-04-16 revision 67580)
[universal.x86_64-darwin20]
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