Le Dimanche, 31 Janvier 2010 15:13:50 -0800, merlyn@stonehenge.com (Randal L. Schwartz) a écrit :
A class is always a singleton. There is only one class named Car in the system. However, there can be many car instances, usually created by sending "new" to "Car".
In the Car class, you'd hold information collectively about all cars, such as the default specifications or number of cars produced.
In each car instance, you'd hold information about a specific car, like its color or owner.
Thanks for pointing that out. In the book's example though, the variable is declared as instance variable. To go along with class variables holding information for all instances, it should instead be declared as class variable isn't it ? (Although it does work like this).
Object subclass: #CarAssembler instanceVariableNames: 'factory' classVariableNames: ''
CarAssembler class>>using: aCarFactory ^self new factory: aCarFactory
That is, if one thinks that a single car factory should be shared amongst all instances of CarAssembler. I think not and I would make it local to each object instance.
Al