# Which messages objects shall respond to? (was: syntactic sug **URL:** \ **Category:** Ruby\ **Created:** [July 18, 2007, 3:56pm UTC](https://www.ruby-forum.com/t/which-messages-objects-shall-respond-to-was-syntactic-sug/109745 "2007-07-18T15:56:10Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![flatekmonkey](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e8c25b/32.png) [@flatekmonkey](https://www.ruby-forum.com/u/flatekmonkey)\ **Post date:** [July 18, 2007, 3:56pm UTC](https://www.ruby-forum.com/t/which-messages-objects-shall-respond-to-was-syntactic-sug/109745/1 "2007-07-18T15:56:10Z")
hi here I am again;) my original (simplified question was): Why Nil#to\_i and not Nil#split. Generally why X#a and not X#b? Well that’s pretty much all, actually there are quite some ways to look at this, but I shall learn and not teach, so I will just be silent for once;) All comments are appreciated. Robert ---
**Author:** ![flatekmonkey](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e8c25b/32.png) [@flatekmonkey](https://www.ruby-forum.com/u/flatekmonkey)\ **Post date:** [July 18, 2007, 4:19pm UTC](https://www.ruby-forum.com/t/which-messages-objects-shall-respond-to-was-syntactic-sug/109745/2 "2007-07-18T16:19:16Z")
Robert D. wrote: > hi here I am again;) > > my original (simplified question was): Why Nil#to\_i and not Nil#split. > Generally why X#a and not X#b? > > Well that’s pretty much all, actually there are quite some ways to > look at this, but I shall learn and not teach, so I will just be > silent for once;) > > All comments are appreciated. > > Robert I’d like Nil only to respond to the same methods as Object does. That said, I’d not have anything against a special syntax to say “go on unless the value is nil” E.g. # this will raise if gets returns nil while line = gets.chomp # just returns nil while line = gets-\>chomp I.e. while . would work normally, -\> would stop the method chain as soon as the receiver is nil and just return nil. Unlike a Nil responding to everything and just returning nil again, this one would leave the coder in control as to specify where he actually wants to know immediatly if he has a nil and where he doesn’t want to know because the result is the same. I don’t know how difficult that would be to implement, though. Regards Stefan ---
**Author:** ![flatekmonkey](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e8c25b/32.png) [@flatekmonkey](https://www.ruby-forum.com/u/flatekmonkey)\ **Post date:** [July 18, 2007, 9:20pm UTC](https://www.ruby-forum.com/t/which-messages-objects-shall-respond-to-was-syntactic-sug/109745/3 "2007-07-18T21:20:42Z")
Hi – On Wed, 18 Jul 2007, Robert D. wrote: > hi here I am again;) > > my original (simplified question was): Why Nil#to\_i and not Nil#split. > Generally why X#a and not X#b? I don’t think there’s a general answer; each case is going to be different. In the case of Nil#to\_i and Nil#split, I think the difference is something like this: #split suggests that nil has the property of “being composite” (i.e., it is something that can split). #to\_i, however, just means that nil has been assigned an arbitrary integer representation. It doesn’t mean that nil has any particular properties. David ---
**Author:** ![flatekmonkey](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e8c25b/32.png) [@flatekmonkey](https://www.ruby-forum.com/u/flatekmonkey)\ **Post date:** [July 18, 2007, 10:04pm UTC](https://www.ruby-forum.com/t/which-messages-objects-shall-respond-to-was-syntactic-sug/109745/4 "2007-07-18T22:04:45Z")
On 7/19/07, Robert D. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Another example, what are the chances that Hash#map returning an array > is more useful than returning it a hash. I have complained about this > “inconsistency” not because it is an inconsistency, but because I feel > it is an useless, counter productive inconsistency. Side effect of #map being defined generically in Enumerable, though I agree that a “structural” map would be more useful for a lot of data structures. martin ---
**Author:** ![flatekmonkey](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e8c25b/32.png) [@flatekmonkey](https://www.ruby-forum.com/u/flatekmonkey)\ **Post date:** [July 18, 2007, 9:44pm UTC](https://www.ruby-forum.com/t/which-messages-objects-shall-respond-to-was-syntactic-sug/109745/5 "2007-07-18T21:44:43Z")
On 7/18/07, removed\_email\_address@domain.invalid [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > different. In the case of Nil#to\_i and Nil#split, I think the > difference is something like this: > > #split suggests that nil has the property of “being composite” (i.e., > it is something that can split). #to\_i, however, just means that nil > has been assigned an arbitrary integer representation. It doesn’t > mean that nil has any particular properties. I have thought about a different approach, what are the chances that the #to\_i message is sent to nil by purpose and what are the chances that it is done by error. I would weight usefulness against purity ( and consistency for that matter ). I simply thought and still think that chances that somebody uses nil#to\_i on purpose are at least as slim as that somebody sends split to nil, and only now I complain about inconsistency. Obviously that was not clear at all. Another example, what are the chances that Hash#map returning an array is more useful than returning it a hash. I have complained about this “inconsistency” not because it is an inconsistency, but because I feel it is an useless, counter productive inconsistency. Yet another example, is it useful that the following is not implemented in standard Ruby class Symbol include Comparable def \<=\> other; to\_s \<=\> other.to\_s end end I feel these are questions that can be discussed in order to make Ruby advance, I am sure that Matz weights CRCs much more serious if there has been discussions like these here… Pitty if we miss these chances… Side note: I just guess that the usage of the word inconsistency has been a bad error of my part, but is it not clear from my strange English that I am not a native speaker ??? Yes you can say: “What, Really, You are not a native speaker, amaaaazing” 😉 > David > Robert ---
**Author:** ![flatekmonkey](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/e8c25b/32.png) [@flatekmonkey](https://www.ruby-forum.com/u/flatekmonkey)\ **Post date:** [July 18, 2007, 10:47pm UTC](https://www.ruby-forum.com/t/which-messages-objects-shall-respond-to-was-syntactic-sug/109745/6 "2007-07-18T22:47:38Z")
On 7/18/07, Martin DeMello [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > On 7/19/07, Robert D. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > > Another example, what are the chances that Hash#map returning an array > > is more useful than returning it a hash. I have complained about this > > “inconsistency” not because it is an inconsistency, but because I feel > > it is an useless, counter productive inconsistency. > > Side effect of #map being defined generically in Enumerable, > that is a good point, it is indeed well documented :), which is > important in theses contexts > though I > agree that a “structural” map would be more useful for a lot of data > structures. > Anyway that is the level of discussion I find more useful 🙂 Robert