Ben's solution worked perfectly for me. Thanks! Also I had a look at Stef's article but still need to read it more carefully.
Thank you all for the references and advice! Eric 2016-07-24 17:48 GMT-03:00 stepharo <steph...@free.fr>: > Have a look at my JOOP'99 article because I explain how to develop > instance specific behavior. > > > Stef > > Le 24/7/16 à 17:14, Eric Velten de Melo a écrit : > > Actually I wanted to have many different object instances with different > behaviours picked at random from a list of available behaviours, but didn't > find practical to create a class for each different method implementation > and delegating to it, since there are many, possibly unlimited valid > behaviours. > > So maybe changing method implementation at runtime is not what I want > because the method implementation will be shared among all instances. What > I had in mind was a functionality similar to prototyped languages like Self > and Javascript in which you could change the behaviour inside the object > and not the class/prototype. > > 2016-07-23 7:35 GMT-03:00 Norbert Hartl <norb...@hartl.name>: > >> Can you elaborate on the reason why want to modify behaviour? And how you >> would like it to happen? >> If the code you want to modify is your own code than you can solve that >> most of time with the things you already have. Your example using a block >> might be altered to be a strategy pattern. That means you keep one ore more >> instance variables for strategy objects. Then you delegate parts of your >> behaviour to those objects. You can based on context exchange those objects >> to adjust behaviour. >> If it is not feasible to change the internal state of an object but you >> know all possible variants you can implement all variations as methods in >> the object. The right method can be invoked by doing a double dispatch with >> another object providing contextual information. >> There are plenty of possibilities so you need to know what is the context >> that is responsible for switching behaviour and the requirements of the >> behaviour modifications. Can you alter the object? Is the number of >> modifications a fixed number? Does the modification need to be thread safe? >> >> Norbert >> >> > Am 23.07.2016 um 00:41 schrieb Eric Velten de Melo <ericvm...@gmail.com >> >: >> > >> > Hello, >> > >> > One thing I try to do often is changing the behaviour of a method >> dynamically at runtime. The current way I do this is by having a block as >> an instance variable and having the method call this block, but I find this >> approach a bit cumbersome. Is there some other way or is this the >> recommended approach? >> > >> > I mean, I suppose methods could be changed dynamically by means of >> reflection somehow, but is this an easy or recommended way of programming >> in Smalltalk? Should slots make things easier? >> > >> > Eric >> >> >> > >
