From: Joseph Alotta Sent: Thursday, May 26, 2016 3:02 PM > On May 26, 2016, at 8:29 AM, Ron Teitelbaum [via Smalltalk] <[hidden email]> > wrote: > > One more question for you. I mentioned returning a newly created instance or > a specific class from a class side method. Can you name another reason why > you would write a method on the class side? When you want the class as a whole to do something. When there is only one instance of an object and other is not desirable or logical. For example, one compiler: two is not practical. One instance of the number Pi. One instance of Nil. Why would you need another? [Ron Teitelbaum] if there is one instance you would still write methods on the instance side. But yes having a class side method that provides your single instance makes sense. > Why would it be a good idea to put a method on the class side instead of the > instance side? (a hint for you, I’m thinking of something where nothing is > returned. (of course in Smalltalk if nothing is returned you get back self, > what I mean is that nothing useful is returned)) Bonus points for 2 or more > answers with or without returning > something J. You would put a method on the class side when the method applies to all instances of the class. For example, Window closeAllWindows. Or Process stopAllProcesses. Or Smalltalk saveImage. I don’t think this is what you had in mind, though. [Ron Teitelbaum] This was exactly what I had in mind. When you have a method that does something to all instances or is needed to find a specific instance it makes sense to implement that as a class side method. Extra credit: Why would you use a class variable? We know that an instance variable is used to store data within the context of an instance. Why would you want to store data in the context of a class? All the best, Ron Teitelbaum Sincerely, Joe. _____ View this message in context: Re: FileDirectory <http://forum.world.st/FileDirectory-tp4897377p4897621.html> Sent from the Squeak - Beginners mailing list archive <http://forum.world.st/Squeak-Beginners-f107673.html> at Nabble.com.
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