Ruby doesn't implement x++ for Fixnum's because ???
in [Ruby]
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From: Tony Arcieri on 8 Nov 2009 14:16 [Note: parts of this message were removed to make it a legal post.] On Sun, Nov 8, 2009 at 11:49 AM, Walton Hoops <walton(a)vyper.hopto.org>wrote: > How? Because they are immutable? That's not special casing, that's just > how the class is designed. I can write an immutable class in Ruby, > without any special casing. > Yes, non-Numeric objects can be immutable. However, Numeric objects can't be mutable. -- Tony Arcieri Medioh/Nagravision
From: Tony Arcieri on 8 Nov 2009 14:32 [Note: parts of this message were removed to make it a legal post.] On Sun, Nov 8, 2009 at 12:20 PM, Seebs <usenet-nospam(a)seebs.net> wrote: > I don't think that gives the right semantics in many cases. It's also > not clear that rebinding works: > > array_example.length++ > > What should this do? > Well, this is a very interesting question, as I discovered something about Ruby I didn't know from this... Say we have: class Foo attr_reader :bar def initialize @bar = 0 end end f = Foo.new f.bar += 1 What do you think the value of a subsequent call to f.bar will be? I was surprised to discover that it indeed 1. Somehow += is mutating the ivar through a supposed "attr_reader" even though there is no corresponding bar= method. In that case += appears to be frobbing the ivar directly. Very strange. Even worse: class Foo def initialize @bar = 0 end def bar @bar + 1 end end f = Foo.new f.bar += 1 Now what do you think the value of a subsequent call to f.bar will be? Indeed, it would be 3! I cannot begin to answer this question because Ruby is doing strange and unexpected things here, at least from my perspective... -- Tony Arcieri Medioh/Nagravision
From: Tony Arcieri on 8 Nov 2009 14:37 [Note: parts of this message were removed to make it a legal post.] On Sun, Nov 8, 2009 at 12:32 PM, Tony Arcieri <tony(a)medioh.com> wrote: > I cannot begin to answer this question because Ruby is doing strange and > unexpected things here, at least from my perspective... > Never mind, bar= was still defined because I was reopening the class. So to answer your question: array_example.length++ ...would attempt to rebind through #length=, and fail if it weren't defined. -- Tony Arcieri Medioh/Nagravision
From: Tony Arcieri on 8 Nov 2009 14:43 [Note: parts of this message were removed to make it a legal post.] On Sun, Nov 8, 2009 at 12:20 PM, Seebs <usenet-nospam(a)seebs.net> wrote: > And which of those operators special-case Numeric? > > Any of them? I don't think so. > Admittedly it would be a first. > If it's to be a rebinding operator, it ought to rebind for everything, not > just for numerics. To borrow a phrase from 37signals, "context is more important than consistency" -- Tony Arcieri Medioh/Nagravision
From: Walton Hoops on 8 Nov 2009 15:15
> From: bascule(a)gmail.com [mailto:bascule(a)gmail.com] On Behalf Of Tony > Yes, non-Numeric objects can be immutable. However, Numeric objects > can't > be mutable. Incorrect. In fact the very first message in this thread provided an example of redifining Fixnum in such a way that it was mutable. |