Activities/Turtle Art/Patching

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Using sqrt

There has been a discussion on the OLPC-sur list about the need for a square root function in Turtle Art. Below, I have documented the process I used for adding this functionality with the hope that others may feel comfortable in emulating me in regard to making changes and enhancements to Sugar and Sugar Activities and sharing those enhancements with the community.

You can download the unofficial Turtleart-11.xo here. The .xo archive can be opened by relabeling it(for example) to a .zip file. Within the archive you find the Python source files and and the images directory images/en/numbers . Python source files can be edited with Python a free download from To run you will also need PyGTK from

Please give me feedback.

The steps

  • I looked at the Turtle Art program installed in Activity/TurtleArt.activity and determined where I needed to make changes. I had to add a new primitive for square root to the file (and also include the sqrt function from the Python math module.
from math import sqrt


    defprim(lc,'sqrt', 1, lambda lc,x: int(sqrt(x)))
  • And I had to define a new brick for square root in and describe the bricks attributes: its size; how it connects to other bricks; and default values.


 'sqrt':    (('num',True,0,20),('num',False,42,20)),
  • Finally, I had to create a graphic for the brick (images/en/numbers/sqrt.gif) and modify the panel for numbers (images/en/numbers/numbersgroup,gif and numbersmask.gif). I made similar changes to the Spanish version (images/es).
The numbers palette
The mask used for selecting bricks
The Spanish version
  • I ran the modified Turtle Art program and made changes until I managed to get it working properly—i.e., I debugged my code. At one point, I sent email to the maintainer with a question, which he promptly answered.
  • In order to push my changes upstream so that others can use them, first I needed to get a local copy of the source code
git-clone git://
Initialized empty Git repository in /home/walter/Desktop/turtleart-activity/.git/
remote: Generating pack...
re mote: Done counting 587 objects.
remote: Deltifying 587 objects...
remote:  100% (587/587) done
remote: Total 587 (delta 129), reused 0 (delta 0)
Receiving objects: 100% (587/587), 5.69 MiB | 882 KiB/s, done.
Resolving deltas: 100% (129/129), done.
  • and make the appropriate changes
I edited and
I also created images/en/numbers/sqrt.gif
and modified images/en/numbers/numbersgroup.gif and numbersmask.gif
(I also made corresponding changes in the images/es tree)
  • and generate a patch
git diff -U > patch
  • and send the patch to the maintainer (Brian Silverman) for review
  • The maintainer made one suggestion:
all looks good to me.

One question. Are you sure you want the "int" of the answer? In the Java version everything is a float, and even in the python version xcor, ycor, and friends are floats. None of the calculations assume ints I don't think.
  • I made the change and did some more testing.
    defprim(lc,'sqrt', 1, lambda lc,x: sqrt(x))
  • next: submit the patch

The patch

diff --git a/images/en/numbers/numbersgroup.gif b/images/en/numbers/numbersgroup
index 3108073..7fe9848 100755
Binary files a/images/en/numbers/numbersgroup.gif and b/images/en/numbers/number
sgroup.gif differ
diff --git a/images/en/numbers/numbersmask.gif b/images/en/numbers/numbersmask.g
index 9509618..ab61c28 100755
Binary files a/images/en/numbers/numbersmask.gif and b/images/en/numbers/numbers
mask.gif differ
diff --git a/images/es/numbers/numbersgroup.gif b/images/es/numbers/numbersgroup
index 2cc5f42..f67fc50 100755
Binary files a/images/es/numbers/numbersgroup.gif and b/images/es/numbers/number
sgroup.gif differ
diff --git a/images/es/numbers/numbersmask.gif b/images/es/numbers/numbersmask.g
index 9509618..ab61c28 100755
Binary files a/images/es/numbers/numbersmask.gif and b/images/es/numbers/numbers
mask.gif differ
diff --git a/ b/
index 0e441bd..bb5850b 100755
--- a/
+++ b/
@@ -22,6 +22,7 @@ import re
 from time import clock
 from operator import isNumberType
 import random
+from math import sqrt
 class taLogo: pass
 from taturtle import *
@@ -269,6 +270,7 @@ def lcNew(tw):
     defprim(lc,'or', None, lambda lc,x,y:x|y)
     defprim(lc,'not', 1, lambda lc,x:not x)
     defprim(lc,'%', None, lambda lc,x,y:x%y)
+    defprim(lc,'sqrt', 1, lambda lc,x: int(sqrt(x)))
     defprim(lc,'clean', 0, lambda lc: clearscreen(
     defprim(lc,'forward', 1, lambda lc, x: forward(, x))
diff --git a/ b/
index 73aa451..19c3c3e 100755
--- a/
+++ b/
@@ -57,13 +57,15 @@ selectors = (
+     ('sqrt','sqrt','sqrt',100),
-     ('not','not','not'),     ('print','print','onearg'))),
+     ('not','not','not'),
+     ('print','print','onearg'))),
   ('flow', 55,
@@ -98,6 +100,7 @@ dockdetails = {
   'ifelse':  (('flow',True,37,5),('logi+',False,80,31),('flow',False,132,79,'['
   'ari':     (('numend',True,12,20),('num',False,39,20)),
   'ari2':    (('numend',True,12,20),('num',False,51,20)),
+  'sqrt':    (('num',True,0,20),('num',False,42,20)),
   'stop':    (('flow',True,37,5),('unavailable',False,0,0)),
   'comp':    (('logi+',True,0,21,'('),('num',False,32,21),('num',False,181,21),
   'random':  (('num',True,0,31,'('),('num',False,28,31),('num',False,150,31),('