> On 02 Dec 2015, at 15:21, Nicolai Hess <[email protected]> wrote: > > > > 2015-12-02 15:03 GMT+01:00 Ben Coman <[email protected]>: > On Wed, Dec 2, 2015 at 12:38 AM, Tudor Girba <[email protected]> wrote: > > Hi, > > > >> On Dec 1, 2015, at 5:13 PM, Max Leske <[email protected]> wrote: > >> > >> @Doru > >> You’re missing the point: #anyOne *fails* for empty collections. > > > > I am not missing the point at all. I am saying that if you want sum: to be > > generic, it cannot assume a specific Zero object. > > > > And sum: should be generic because of its name. > > I am missing understanding the other use cases. Can you describe > further the generic nature of #sum & #sum: ? I would have thought by > default they only applied to numbers. > > sum can be applied to anything that supports #+, not only numbers > sum: can be applied to any collection with a block that return some object > that supports #+ > > therefore you can not assume 0 (<- a number) is a proper initial value > therefore you *need* to work with #anyOne > and as you can not assume a proper initial value, you can not assume a > default value for empty collections > -> it should throw an error. If you (the caller of the function) knows what > to do with an empty collection you have > to check, or call inject:into: directly, with a proper initial value.
I am sorry but I am getting really tired of this, you should read what is being said. I am not suggesting to stop using #anyOne because I like why it is there and what it can do. The change I want is what happens with an empty collection when using the simplest selector, #sum. I do not want to say to some collection of numbers #sumIfEmpty: [0], because summing numbers starting from zero is the most common case and everybody expects that, hence the unary selector fits. I want the less common cases to use the more complicated API, as in some collection of colors #sumIfEmpty: [ Color black ] In my book that is common sense API design. Doing that I do no take anything away, because today you already have to make sure the collection is not empty. The only change would be in the error behaviour. I think that is a reasonable price to pay. Instead of having #anyOne fail, it will say that #+ cannot add 0 to some object, and in a comment we can point to the alternative API. http://izquotes.com/quote/242740 right ? > cheers -ben > > > > >>> On 01 Dec 2015, at 15:31, Esteban A. Maringolo <[email protected]> > >>> wrote: > >>> > >>> I don't want to be heretic (or too orthodox), but why not to delegate > >>> this behavior to other class (an iterator maybe?). > >>> > >>> It's too tempting adding these convenience methods to Collection > >>> and/or subclasses, but anything that requires an explicit protocol of > >>> its elements is wrong, IMO. > >>> > >>> something like aCollection arithmetic sum: [...] or.... aCollection > >>> arithmetic avg. > >> > >> > >> Interesting thought! > > > > +100 > > > > Doru > > > >>> > >>> My two cents for this. > >>> > >>> Regards! > >>> > >>> > >>> Esteban A. Maringolo > >>> > >> > >> > > > > -- > > www.tudorgirba.com > > > > "Every thing has its own flow." > > > > > > > > > >
