Make turtle.pensize smarter

Feature or enhancement

Proposal:

The turtle.pensize doc says:

turtle.pensize(width=None)
    Parameters:

        width – a positive number

However, if you put a non-positive number, the function will accept it without any error or warning.

Afterwards, a draw action (like forward) will raise an exception. See below.

>>> import turtle
>>> turtle.pensize(-1)
>>> turtle.forward(100)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 8, in forward
  File "/home/adorilson/anaconda3/lib/python3.12/turtle.py", line 1636, in forward
    self._go(distance)
  File "/home/adorilson/anaconda3/lib/python3.12/turtle.py", line 1597, in _go
    self._goto(ende)
  File "/home/adorilson/anaconda3/lib/python3.12/turtle.py", line 3248, in _goto
    screen._drawline(self.drawingLineItem,
  File "/home/adorilson/anaconda3/lib/python3.12/turtle.py", line 543, in _drawline
    self.cv.itemconfigure(lineitem, width=width)
  File "<string>", line 1, in itemconfigure
  File "/home/adorilson/anaconda3/lib/python3.12/tkinter/__init__.py", line 2988, in itemconfigure
    return self._configure(('itemconfigure', tagOrId), cnf, kw)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/adorilson/anaconda3/lib/python3.12/tkinter/__init__.py", line 1712, in _configure
    self.tk.call(_flatten((self._w, cmd)) + self._options(cnf))
_tkinter.TclError: bad screen distance "-1"
>>>

My suggestion is pensize (and probably others) raises a TurtleGraphicsError if the width argument is less than 1.

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

https://discuss.python.org/t/improving-the-turtle-library/61840/18

Linked PRs

• gh-135268

Comece em turtle.py, na implementação de pensize, e compare o tratamento do requisito documentado de uma largura positiva com a falha relatada de forward. Revise a discussão vinculada e gh-135268 antes de prosseguir; considera-se concluído quando larguras não positivas inválidas são tratadas no momento de pensize, em vez de falharem durante uma ação de desenho posterior.