2010/10/11 Levente Uzonyi <le...@elte.hu>: > On Mon, 11 Oct 2010, Lukas Renggli wrote: > >>> Object>>value >>> ^self >>> >>> What actually shown here is a use of duck typing, because any object, >>> which implemets #value, could be safely passed >>> as argument to #ifTrue:ifFalse: message. >>> It is well consistent with language design. >> >> Magritte implemented Symbol>>#value: for a while before any Smalltalk >> had this is their standard library. I must admit that I liked it in >> the beginning, but in the long run I realized that ... >> >> 1. It is not easily understandable for newbies. > > That's true. >
Well, it depends. Very newbies can understand it because they trust the words. My son did. More advanced newbies can wonder how the hell this could work eventually, because they can differentiate a regular message and a literal #symbol. It's true that writing code is another matter. Why and when to use a block a message or a Symbol ? Maybe a newbie could be tempted to write: x > 1 and: #even. which currently does not work. >> 2. It quickly leads to very unreadable, hard to understand and hard to >> refactor code. >> 3. It is very limiting in itself and quickly leads to other hacks >> (like to replace sort blocks). > > That "hack" is really cool IMO. The code is easily understood by anyone: > > #(4 1 3 5 2) sort: #<=. > >> 4. #value and friends should be only understood by objects that can be >> evaluated (certainly not by Object). A symbol (name) by itself cannot >> be evaluated. >> >> I eventually removed Symbol>>#value: for good. Re-occuring questions >> in the mailing list disappeared. > > That's strange, because Symbol >> #value: was added to Squeak in 2006 during > the developement of 3.9. > > > Levente > >> >> Therefor I strongly suggest to remove #value, #value:, and friends >> from all objects that are not self-evaluable. BlockClosure and >> MessageSend are self-evaluable. Only there it makes sense. >> >> If people are too lazy to create a block where something >> self-evaluable is needed they should use a programming language >> designed for cryptic code. Creating a block closure in Smalltalk is >> concise and makes clear what happens easily. A symbol does not, you >> need to exactly understand how this dispatches with various objects. >> >> Lukas >> >> >> -- >> Lukas Renggli >> www.lukas-renggli.ch >> >> _______________________________________________ >> Pharo-project mailing list >> Pharo-project@lists.gforge.inria.fr >> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project > > _______________________________________________ > Pharo-project mailing list > Pharo-project@lists.gforge.inria.fr > http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project > _______________________________________________ Pharo-project mailing list Pharo-project@lists.gforge.inria.fr http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
