Mensanator schrieb:
It didn't form 2.5 to 2.6 (at least not intentionally). But with the
indroduction of the TurtleScreen class and the Screen class/object
(singleton) a few of the turtle methods were also implemented as screen
methods and as turtle methods declared deprecated (see docs of Python
2.6). These deprecated turtle methods do not occur as turtle methods any
more in Python 3.x.
More info.
Yes, there is no tracer attribute...when the object is created.
But watch this (Python 3.1):
import turtle
tooter = turtle.Turtle()
tooter.tracer
Traceback (most recent call last):
File "<pyshell#2>", line 1, in <module>
tooter.tracer
AttributeError: 'Turtle' object has no attribute 'tracer'
tooter.hideturtle()
tooter.speed('fast')
turtle.update()
turtle.tracer
<function tracer at 0x013E0ED0>
Now, after setting hide, speed, update, a tracer exists.
No,
>>> import turtle
>>> turtle.tracer
<function tracer at 0x013CFE40>
>>> help(turtle.tracer)
Help on function tracer in module turtle:
tracer(n=None, delay=None)
Turns turtle animation on/off and set delay for update drawings.
Optional arguments:
n -- nonnegative integer
delay -- nonnegative integer
If n is given, only each n-th regular screen update is really
performed.
(Can be used to accelerate the drawing of complex graphics.)
Second arguments sets delay value.)
Example:
>>> tracer(8, 25)
>>> dist = 2
>>> for i in range(200):
fd(dist)
rt(90)
dist += 2
>>>
The reason for this is, that the turtle module (the new one as well as
the old one) has a vers special design: The methods of class Turtle are
also available as functions (which are in fact methods calls of an
anonymous turtle). The same holds for the methods of TurtleScreen.
The intention behind this design is that you can use the module in an
OOP way as well as with procedural programming (especially for beginners).
When using objects I normally use
from turtle import Turtle, Screen
screen = Screen()
# that creates singleton object, the screen the turtle acts on
and I create as many turtles as I need from the Turtle class
So turtle.tracer() doesn't make sense anymore
Is that supposed to happen? That explains why there was no error
when I set the turtle attribute instead of the screen attribute.
You do not 'set the turtle attribute', you call the tracer function of
the turtle module
And, of course, setting the turtle attribute accomplishes nothing,
as actual tracing is controlled by the screen attribute as you say.
Among them is the tracer method, which in fact does not control single
turtle objects but all the turtles on a given screen.
So there is an icompatibility beween 2.6 and 3.x
But as far as I have understood, this doesn't concern the problem
reported by mensator.
Only that the problem is hidden when tracing is off, as the nhops
variable is never evaluated when trace is off.
Nevertheless I'd like to see a working Python 2.5 version of your script.
Regards,
Gregor
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