binary selectors ambiguity and space

Hans-Martin Mosner hmm at
Wed May 17 15:58:27 UTC 2006

Duncan Mak wrote:

> I have always wondered why the standard image doesn't come with a next 
> method and an increment method for Integers, where next would answer x 
> + 1 and increment would set x to be x + 1.

The first is easy, but in my opinion does not add much value - "aNumber 
next" does not help me understand the code better than "aNumber + 1" 
does. And of course, it re-uses a selector which is already used in the 
stream hierarchy and means something completely different.

The second one is not possible with Smalltalk's semantics. Messages are 
sent to objects, not to variables. So whatever message you send to 
variable x, it can't cause x to point to another object (with the 
exception of #become: but that's a special case). Since numeric objects 
are immutable, you need to have the assignment x := x+1 either 
implicitly or explicitly somewhere.

I'd like to know concrete use cases where you would prefer an increment 
method over an explicit x := x+1. My gut feeling is that such cases 
probably could be handled even better by still other constructs (for 
example, collections or streams), but of course this can't be said 
generally for all cases.


More information about the Squeak-dev mailing list