gh-88773: Added teleport method to Turtle library (#103974)

Add a `teleport` method to `turtle` module turtle instances that acts a lot like `goto`, _but_ ensures the pen is up while warping to the new position to and can control shape filling behavior as part of the jump.

Based on an educator user feature request.

---------

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
Co-authored-by: Hugo van Kemenade <hugovk@users.noreply.github.com>
Co-authored-by: Gregory P. Smith <greg@krypto.org>

Doc/library/turtle.rst

@@ -107,6 +107,7 @@ Turtle motion
       | :func:`right` | :func:`rt`
       | :func:`left` | :func:`lt`
       | :func:`goto` | :func:`setpos` | :func:`setposition`
+      | :func:`teleport`
       | :func:`setx`
       | :func:`sety`
       | :func:`setheading` | :func:`seth`
@@ -372,6 +373,44 @@ Turtle motion
        (0.00,0.00)
 
 
+.. function:: teleport(x, y=None, *, fill_gap=False)
+
+   :param x: a number or ``None``
+   :param y: a number or ``None``
+   :param fill_gap: a boolean
+
+   Move turtle to an absolute position. Unlike goto(x, y), a line will not
+   be drawn. The turtle's orientation does not change. If currently
+   filling, the polygon(s) teleported from will be filled after leaving,
+   and filling will begin again after teleporting. This can be disabled
+   with fill_gap=True, which makes the imaginary line traveled during
+   teleporting act as a fill barrier like in goto(x, y).
+
+   .. doctest::
+      :skipif: _tkinter is None
+      :hide:
+
+      >>> turtle.goto(0, 0)
+
+   .. doctest::
+      :skipif: _tkinter is None
+
+       >>> tp = turtle.pos()
+       >>> tp
+       (0.00,0.00)
+       >>> turtle.teleport(60)
+       >>> turtle.pos()
+       (60.00,0.00)
+       >>> turtle.teleport(y=10)
+       >>> turtle.pos()
+       (60.00,10.00)
+       >>> turtle.teleport(20, 30)
+       >>> turtle.pos()
+       (20.00,30.00)
+
+   .. versionadded: 3.12
+
+
 .. function:: setx(x)
 
    :param x: a number (integer or float)
@@ -537,8 +576,7 @@ Turtle motion
       :skipif: _tkinter is None
 
       >>> turtle.color("blue")
-      >>> turtle.stamp()
-      11
+      >>> stamp_id = turtle.stamp()
       >>> turtle.fd(50)
 
 
@@ -575,15 +613,8 @@ Turtle motion
    .. doctest::
 
       >>> for i in range(8):
-      ...     turtle.stamp(); turtle.fd(30)
-      13
-      14
-      15
-      16
-      17
-      18
-      19
-      20
+      ...     unused_stamp_id = turtle.stamp()
+      ...     turtle.fd(30)
       >>> turtle.clearstamps(2)
       >>> turtle.clearstamps(-2)
       >>> turtle.clearstamps()

Lib/test/test_turtle.py

@@ -267,6 +267,14 @@ def test_goto(self):
         self.assertAlmostEqual(self.nav.xcor(), 100)
         self.assertAlmostEqual(self.nav.ycor(), -100)
 
+    def test_teleport(self):
+        self.nav.teleport(20, -30, fill_gap=True)
+        self.assertAlmostEqual(self.nav.xcor(), 20)
+        self.assertAlmostEqual(self.nav.ycor(), -30)
+        self.nav.teleport(-20, 30, fill_gap=False)
+        self.assertAlmostEqual(self.nav.xcor(), -20)
+        self.assertAlmostEqual(self.nav.ycor(), 30)
+
     def test_pos(self):
         self.assertEqual(self.nav.pos(), self.nav._position)
         self.nav.goto(100, -100)
@@ -440,6 +448,18 @@ def test_showturtle_hideturtle_and_isvisible(self):
         tpen.showturtle()
         self.assertTrue(tpen.isvisible())
 
+    def test_teleport(self):
+
+        tpen = turtle.TPen()
+
+        for fill_gap_value in [True, False]:
+            tpen.penup()
+            tpen.teleport(100, 100, fill_gap=fill_gap_value)
+            self.assertFalse(tpen.isdown())
+            tpen.pendown()
+            tpen.teleport(-100, -100, fill_gap=fill_gap_value)
+            self.assertTrue(tpen.isdown())
+
 
 if __name__ == '__main__':
     unittest.main()

Lib/turtle.py

@@ -135,7 +135,7 @@
         'pu', 'radians', 'right', 'reset', 'resizemode', 'rt',
         'seth', 'setheading', 'setpos', 'setposition', 'settiltangle',
         'setundobuffer', 'setx', 'sety', 'shape', 'shapesize', 'shapetransform', 'shearfactor', 'showturtle',
-        'speed', 'st', 'stamp', 'tilt', 'tiltangle', 'towards',
+        'speed', 'st', 'stamp', 'teleport', 'tilt', 'tiltangle', 'towards',
         'turtlesize', 'undo', 'undobufferentries', 'up', 'width',
         'write', 'xcor', 'ycor']
 _tg_utilities = ['write_docstringdict', 'done']
@@ -1614,6 +1614,13 @@ def _goto(self, end):
         """move turtle to position end."""
         self._position = end
 
+    def teleport(self, x=None, y=None, *, fill_gap: bool = False) -> None:
+        """To be overwritten by child class RawTurtle.
+        Includes no TPen references."""
+        new_x = x if x is not None else self._position[0]
+        new_y = y if y is not None else self._position[1]
+        self._position = Vec2D(new_x, new_y)
+
     def forward(self, distance):
         """Move the turtle forward by the specified distance.
 
@@ -2293,6 +2300,15 @@ def fillcolor(self, *args):
         else:
             return self._color(self._fillcolor)
 
+    def teleport(self, x=None, y=None, *, fill_gap: bool = False) -> None:
+        """To be overwritten by child class RawTurtle.
+        Includes no TNavigator references.
+        """
+        pendown = self.isdown()
+        if pendown:
+            self.pen(pendown=False)
+        self.pen(pendown=pendown)
+
     def showturtle(self):
         """Makes the turtle visible.
 
@@ -2710,6 +2726,54 @@ def _cc(self, args):
         if not ((0 <= r <= 255) and (0 <= g <= 255) and (0 <= b <= 255)):
             raise TurtleGraphicsError("bad color sequence: %s" % str(args))
         return "#%02x%02x%02x" % (r, g, b)
+
+    def teleport(self, x=None, y=None, *, fill_gap: bool = False) -> None:
+        """Instantly move turtle to an absolute position.
+
+        Arguments:
+        x -- a number      or     None
+        y -- a number             None
+        fill_gap -- a boolean     This argument must be specified by name.
+
+        call: teleport(x, y)         # two coordinates
+        --or: teleport(x)            # teleport to x position, keeping y as is
+        --or: teleport(y=y)          # teleport to y position, keeping x as is
+        --or: teleport(x, y, fill_gap=True)          
+                                     # teleport but fill the gap in between
+
+        Move turtle to an absolute position. Unlike goto(x, y), a line will not
+        be drawn. The turtle's orientation does not change. If currently
+        filling, the polygon(s) teleported from will be filled after leaving,
+        and filling will begin again after teleporting. This can be disabled
+        with fill_gap=True, which makes the imaginary line traveled during 
+        teleporting act as a fill barrier like in goto(x, y).
+
+        Example (for a Turtle instance named turtle):
+        >>> tp = turtle.pos()
+        >>> tp
+        (0.00,0.00)
+        >>> turtle.teleport(60)
+        >>> turtle.pos()
+        (60.00,0.00)
+        >>> turtle.teleport(y=10)
+        >>> turtle.pos()
+        (60.00,10.00)
+        >>> turtle.teleport(20, 30)
+        >>> turtle.pos()
+        (20.00,30.00)
+        """
+        pendown = self.isdown()
+        was_filling = self.filling()
+        if pendown:
+            self.pen(pendown=False)
+        if was_filling and not fill_gap:
+            self.end_fill()
+        new_x = x if x is not None else self._position[0]
+        new_y = y if y is not None else self._position[1]
+        self._position = Vec2D(new_x, new_y)
+        self.pen(pendown=pendown)
+        if was_filling and not fill_gap:
+            self.begin_fill()   
 
     def clone(self):
         """Create and return a clone of the turtle.

Misc/NEWS.d/next/Library/2023-04-28-18-04-23.gh-issue-88773.xXCNJw.rst

@@ -0,0 +1 @@
+Added :func:`turtle.teleport` to the :mod:`turtle` module to move a turtle to a new point without tracing a line, visible or invisible.  Patch by Liam Gersten.