python-3.6.zip added from Github

README.cosmo contains the necessary links.

third_party/python/Tools/demo/hanoi.py

@@ -0,0 +1,154 @@
+#!/usr/bin/env python3
+
+"""
+Animated Towers of Hanoi using Tk with optional bitmap file in background.
+
+Usage: hanoi.py [n [bitmapfile]]
+
+n is the number of pieces to animate; default is 4, maximum 15.
+
+The bitmap file can be any X11 bitmap file (look in /usr/include/X11/bitmaps for
+samples); it is displayed as the background of the animation.  Default is no
+bitmap.
+"""
+
+from tkinter import Tk, Canvas
+
+# Basic Towers-of-Hanoi algorithm: move n pieces from a to b, using c
+# as temporary.  For each move, call report()
+def hanoi(n, a, b, c, report):
+    if n <= 0: return
+    hanoi(n-1, a, c, b, report)
+    report(n, a, b)
+    hanoi(n-1, c, b, a, report)
+
+
+# The graphical interface
+class Tkhanoi:
+
+    # Create our objects
+    def __init__(self, n, bitmap = None):
+        self.n = n
+        self.tk = tk = Tk()
+        self.canvas = c = Canvas(tk)
+        c.pack()
+        width, height = tk.getint(c['width']), tk.getint(c['height'])
+
+        # Add background bitmap
+        if bitmap:
+            self.bitmap = c.create_bitmap(width//2, height//2,
+                                          bitmap=bitmap,
+                                          foreground='blue')
+
+        # Generate pegs
+        pegwidth = 10
+        pegheight = height//2
+        pegdist = width//3
+        x1, y1 = (pegdist-pegwidth)//2, height*1//3
+        x2, y2 = x1+pegwidth, y1+pegheight
+        self.pegs = []
+        p = c.create_rectangle(x1, y1, x2, y2, fill='black')
+        self.pegs.append(p)
+        x1, x2 = x1+pegdist, x2+pegdist
+        p = c.create_rectangle(x1, y1, x2, y2, fill='black')
+        self.pegs.append(p)
+        x1, x2 = x1+pegdist, x2+pegdist
+        p = c.create_rectangle(x1, y1, x2, y2, fill='black')
+        self.pegs.append(p)
+        self.tk.update()
+
+        # Generate pieces
+        pieceheight = pegheight//16
+        maxpiecewidth = pegdist*2//3
+        minpiecewidth = 2*pegwidth
+        self.pegstate = [[], [], []]
+        self.pieces = {}
+        x1, y1 = (pegdist-maxpiecewidth)//2, y2-pieceheight-2
+        x2, y2 = x1+maxpiecewidth, y1+pieceheight
+        dx = (maxpiecewidth-minpiecewidth) // (2*max(1, n-1))
+        for i in range(n, 0, -1):
+            p = c.create_rectangle(x1, y1, x2, y2, fill='red')
+            self.pieces[i] = p
+            self.pegstate[0].append(i)
+            x1, x2 = x1 + dx, x2-dx
+            y1, y2 = y1 - pieceheight-2, y2-pieceheight-2
+            self.tk.update()
+            self.tk.after(25)
+
+    # Run -- never returns
+    def run(self):
+        while 1:
+            hanoi(self.n, 0, 1, 2, self.report)
+            hanoi(self.n, 1, 2, 0, self.report)
+            hanoi(self.n, 2, 0, 1, self.report)
+            hanoi(self.n, 0, 2, 1, self.report)
+            hanoi(self.n, 2, 1, 0, self.report)
+            hanoi(self.n, 1, 0, 2, self.report)
+
+    # Reporting callback for the actual hanoi function
+    def report(self, i, a, b):
+        if self.pegstate[a][-1] != i: raise RuntimeError # Assertion
+        del self.pegstate[a][-1]
+        p = self.pieces[i]
+        c = self.canvas
+
+        # Lift the piece above peg a
+        ax1, ay1, ax2, ay2 = c.bbox(self.pegs[a])
+        while 1:
+            x1, y1, x2, y2 = c.bbox(p)
+            if y2 < ay1: break
+            c.move(p, 0, -1)
+            self.tk.update()
+
+        # Move it towards peg b
+        bx1, by1, bx2, by2 = c.bbox(self.pegs[b])
+        newcenter = (bx1+bx2)//2
+        while 1:
+            x1, y1, x2, y2 = c.bbox(p)
+            center = (x1+x2)//2
+            if center == newcenter: break
+            if center > newcenter: c.move(p, -1, 0)
+            else: c.move(p, 1, 0)
+            self.tk.update()
+
+        # Move it down on top of the previous piece
+        pieceheight = y2-y1
+        newbottom = by2 - pieceheight*len(self.pegstate[b]) - 2
+        while 1:
+            x1, y1, x2, y2 = c.bbox(p)
+            if y2 >= newbottom: break
+            c.move(p, 0, 1)
+            self.tk.update()
+
+        # Update peg state
+        self.pegstate[b].append(i)
+
+
+def main():
+    import sys
+
+    # First argument is number of pegs, default 4
+    if sys.argv[1:]:
+        n = int(sys.argv[1])
+    else:
+        n = 4
+
+    # Second argument is bitmap file, default none
+    if sys.argv[2:]:
+        bitmap = sys.argv[2]
+        # Reverse meaning of leading '@' compared to Tk
+        if bitmap[0] == '@': bitmap = bitmap[1:]
+        else: bitmap = '@' + bitmap
+    else:
+        bitmap = None
+
+    # Create the graphical objects...
+    h = Tkhanoi(n, bitmap)
+
+    # ...and run!
+    h.run()
+
+
+# Call main when run as script
+if __name__ == '__main__':
+    main()