Canvas Object Tags: Help for Rookie

[John Smith]

Pythoners:

I am goofing around with the canvas class and trying to reference line
objects drawn on a canvas by their tags.  I thought the easiest appraoch
would be to give each new line an tag set by an integer counter.  A short
version of my code looks like:

class myCanvas:

def __init__(self, root):

    tagid = 0

>>>Some code

    self.btn = Button(self.frame, text='OK')

    self.btn.pack(side=LEFT)

    self.btn.bind('<Button-1>', self.lineupdate(tagid))

>>>Some code

def lineupdate(self, tag, event=None):

    coordlist = self.canvas.coords(tag)

    lastx = coordlist[2]

    lasty = coordlist[3]

    tagid = tagid + 1

    newx = lastx + 50

    newy = lasty - 50

    self.canvas.create_line(lastx, lasty, newx, newy, arrow='last', width=2,
fill='red', tags=self.tagid)

def firstline(self):

    self.canvas.create_line(10, 10, 200, 200, arrow='last', width=2,
fill='red', tags=self.tagid)



mc = myCanvas(root)

mc.firstline()

root.mainloop()



A get an attribute error in the lineupdate function for the
self.canvas.coords(tag) function.  My understanding is that the function
should return the coordinates of the line object.



Any help?