A student writes to ask several excellent questions:
Hi Dr Lyon
Read thru the notes and I have the following questions.
We could discuss them
during the class
Q1 What is Platform Independence and what is meant by Multi threading?
Q2 Would like some more information on Smalltalk and Zetalisp.
Q3 Why can't we always instance a class without knowing the class
name?
Q4 What is " Delegation Pattern "? Please explain.
Platform Independence means that code is portable. The
degree to which this is obtained depends on the implementation
of the supporting technology.
Multi-threading refers to a shared memory, low-overhead,
context switch technology able to simulate concurrent processes.
(I shall elaborate on this more later in the term).
Smalltalk and Zetalisp are older languages that are able to
support object oriented design. They are both lisp variants.
You ask:
Q3 Why can't we always instance a class without knowing the class
name?
If you try to instance a class, you typically
say:
ClassName c = new ClassName();
So, if you don't know the ClassName, you typically can't
instance the class...
You ask:
Q4 What is " Delegation Pattern "? Please explain.
Delegation refers to a class that makes use of another
instance in order to perform some computation.
For example:
The mad bomber has a bomb. The mad bomber does
not explode, only trigger the explosion. The
bomb does the exploding. Thus, the bomber
delegates the exploding to the bomb.
So, if I tell the bomber, "explode the bomb",
the bomber knows how to get the bomb to do the exploding.
This too, is a topic that will appear later in the term.
Regards,
- D
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