> one of my main message in my course is to have variables with a type!
> so "def x" is not encouraged (not even taught)!
Well, that's arguable at best.
Whilst declaring variables is highly _practical_ for it helps to prevent typos
and allows both the IDE and compiler to assist the programmer, _conceptually_
it is very wrong. The concept of object programming is that an object is an
object is an object; all objects are conceptually equal, and each object can be
sent any message (well, the Java howler of “calling methods” instead of the
proper paradigm of “sending messages” does not help either :( ).
All in all, given you don't teach Groovy but programming, I would strongly
recommend to use some variant of Smalltalk instead -- it is less practical for
everyday purposes, but allows the students to grok the principles of OOP _much_
better than anything Java-based ever might.
> now if you have a factory that returns the proper class and you assign it to
> a variable typed with a subclass it won't work.
===
26 /tmp> <w.groovy
class Localizeděščřžýáíí extends LinkedList { }
class Factory { static LinkedList list() { return new LinkedList() } }
Localizeděščřžýáíí ěěě=Factory.list()
ěěě<<"Actually, it does work, though in Java-based language it's a small
miracle"
println "${ěěě.class.simpleName} contains $ěěě"
27 /tmp> groovy w
Localizeděščřžýáíí contains [Actually, it does work, though in Java-based
language it's a small miracle]
28 /tmp>
===
?
All the best,
OC
