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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