CS 394P: Object-Oriented Programming Exercise
Due: March 28, 2005.
The goals of this exercise are to gain experience in using
object-oriented programming to write generic programs, and to
investigate performance of object-oriented code.
The graphical part of this assignment should be done using xgcl (Gnu Common Lisp,
GCL, with an interface to X windows), /p/bin/xgcl on a
Linux or Sun workstation. Enter (load "/projects/cs394p/dw.lsp")
as the first command to Lisp to load all the files needed.
(File names shown below are in the directory /projects/cs394p/.)
You can use xdvi /projects/cs394p/dwdoc.dvi to view documentation
of the drawing primitives.
- Examine the code in the file oops.lsp and
understand how it works. Example files for use with this
code are oopexa.lsp, oopexa.tst, planet.lsp,
- Add to the file oopexa.lsp a method move-by
with arguments deltax and deltay that will modify a
vector by incrementing its x and y values by the
specified amounts. This method should work for any kind of vector.
Add methods to make the examples in the file oopexa.tst work.
- Examine the execution overhead of this object-oriented
system experimentally as follows.
For this part of the exercise, you should use plain GCL, /p/bin/gcl.
Enter (load "/projects/cs394p/dwb.lsp") to load files for use
with this Lisp.
Consider the functions t1 through
t4 in the file ooptime.lsp ;
time these functions using (time code) and using a suitable
number of repetitions n as the argument to the functions..
Compile all functions and methods; the function (compile-methods)
will compile all methods. These functions should allow you to compare:
- the amount of time required to execute the loop and perform the additions
- the overhead of a function call
- the overhead of a message send
- the overhead of creating a new object.
- Add to the file drawobj.lsp a method to draw some
other kind of object. Verify that the slide message works for
- Add a composite-object that is composed of multiple drawable
objects, each of which has an offset from the offset of the composite
object as a whole. Implement a method add-object to add a new object
to the composite object at specified offsets, and a draw method.
Verify that the slide message works for a composite object and that
a composite object can have composite components.
- Replace the + method for vector with a method
that is more general. Assume that the definition of vector
addition is to make a new instance of the same type as the first vector,
and to set each of its slots to the value obtained by adding the slot value
of the first vector to the corresponding message value of the second
vector; of course, the addition should also be done by a message.
You can use class-of and slot-names to find out the
class of the first arguemnt and the names of its slots.
Demonstrate that your single generic function for vector addition works
for xyvector, xyzvector, rthvector,
vectorvector, and appropriate combinations of these (e.g.,
xyvector combined with rthvector).
Investigate the time required for this generic function and compare it
with the time required for the + method given in oopexa.lsp.