Re: finding name of instances created
Craig Ringer wrote:
On Fri, 2005-01-21 at 16:13 -0800, Andr wrote:
Short version of what I am looking for:
Given a class public_class which is instantiated a few times e.g.
a = public_class()
b = public_class()
c = public_class()
I would like to find out the name of the instances so that I could
create a list of them e.g.
['a', 'b', 'c']
[snip]
I'm not really able to grasp what you're trying to do (but others
might). It wouldn't hurt if you could post a description of what you're
actually trying to achieve - /why/ you want this - as that can often be
very helpful both in understanding what you're thinking and in
suggesting a suitable approach or alternative.
Ok, here it goes... I am designing a learning environment for Python.
(See rur-ple.sourceforge.org for details of a *very early, still buggy*
relase). I have a world in which a
robot can accomplish four built-in instructions: move(), turn_left(),
pick_beeper(), put_beeper().
turn_left() corresponds to a 90 degree left turn. One can define a
function to simulate a 90 degree right turn as follows:
def turn_right():
turn_left()
turn_left()
turn_left()
and call it as a built-in instruction thereafter.
By giving more and more complicated tasks for the robot to accomplish,
one can learn various programming concepts using python syntax:
def (as above), while, if, else, elif, ..
I have all of that working well so far (not on sourceforge yet).
Next, I want to introduce
the concept of classes and objects, again using python's syntax.
Behind the scene, I have something like:
robot_dict = { 'robot' = CreateRobot( ..., name = 'robot') }
and have mapped move() to correspond to
robot_dict['robot'].move()
(which does lots of stuff behind the scene.)
I have tested robot_dict[] with more than one robot (each with
its own unique name) and am now at the point where I would like
to have the ability to interpret something like:
alex = CreateRobot()
anna = CreateRobot()
alex.move()
anna.move()
etc. Since I want the user to learn Python's syntax, I don't
want to require him/her to write
alex = CreateRobot(name = 'alex')
to then be able to do
alex.move()
I have tried various things at the interpreter, found that
to a class 'a', I could see the instance 'b' created in
locals():
'a': class '__main__.a', 'b': __main__.a object at 0x011515D0
which tells me that there must be a way to catch b's name as it is
created, and do what I want to do.
Does this clarify what I am trying to do and why?
Andr
--
http://mail.python.org/mailman/listinfo/python-list
Linguistic challenge: name this program
In 1981, Richard Pattis wrote a delightful little book titled Karel the Robot, a Gentle Introduction to the Art of Programming. Pattis's Karel the Robot was named after the author Karel Capek, who popularized the word robot in his play Rossum's Universal Robots. Pattis's approach was to introduce a robot who could follow 5 basic instructions and be taught to accomplish tasks of increasing complexity. A few years ago, a first implementation of Karel the Robot in Python was created and called PyKarel. A second, newer implementation is called Guido van Robot (GvR for short), and is available at gvr.sourceforge.net. Work is currently underway by the developpers of GvR to produce a new-and-improved version. I have been working on my own (better ;-) version (sometimes collaborating with the GvR folks) in order to learn Python. It is now 90% finished. It is meant to be a complete environment to learn about programming concepts, from simple sequences of instruction to OOP. Given the origin of Pattis's name (Rossum's Universal Robot) and the name of Python's BDFL, I find it difficult to think of a better name than Guido van Robot to name a programming environment in which one uses Python to teach a robot new tricks! (Hat's off to Steve Howell for this one). Yet, I want a clever name for my version. Any suggestions? Andre Roberge -- http://mail.python.org/mailman/listinfo/python-list
exec and global puzzle
I have the following two files: #--testexec.py-- def exec_code(co): try: exec co except: print error #-- test.py-- import thread import testexec import time code = def a():\n print 'a'\n\n +\ def c():\n a()\n\nc() code2 = def a():\n print 'a'\n\n +\ def c():\n global a\n a()\n\nc() print exec code - no global exec code print exec from thread - no global thread.start_new(testexec.exec_code, (code,)) time.sleep(1) print \n exec code2 - with global exec code2 print exec from thread - with global thread.start_new(testexec.exec_code, (code2,)) #--- Here's the output when I execute test.py: exec code - no global a exec from thread - no global error exec code2 - with global a exec from thread - with global a #- Without the global statement, I get an error when trying to execute the code. I don't understand why I need to use the global statement within the definition of c() in order for it to know what a() is. If I define exec_code() within test.py and use it there, I do not get any error, with or without the use of a global statement. Andre -- http://mail.python.org/mailman/listinfo/python-list
