turtle.dot(size="blue") has a weird behaviour

[adorilson]

Bug description:

The turtle.dot's documentation says:

turtle.dot()
turtle.dot(size)
turtle.dot(color, /)
turtle.dot(size, color, /)
turtle.dot(size, r, g, b, /)

    Parameters:

            size – an integer >= 1 (if given)

            color – a colorstring or a numeric color tuple

However, turtle.dot(size="blue") doesn't raise an exception. Instead of this, the color is changed to blue.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

[StanFromIreland]

Intentional, however:

cpython/Lib/turtle.py

Lines 3501 to 3503 in 4ac16dd

	if isinstance(size, (str, tuple)):
	color = self._colorstr(size)
	size = self._pensize + max(self._pensize, 4)

So I shall mark this as a feature.

[JanEricNitschke]

Yeah, this is the runtime code:

    def dot(self, size=None, *color):
        """Draw a dot with diameter size, using color.

        Optional arguments:
        size -- an integer >= 1 (if given)
        color -- a colorstring or a numeric color tuple

        Draw a circular dot with diameter size, using color.
        If size is not given, the maximum of pensize+4 and 2*pensize is used.

        Example (for a Turtle instance named turtle):
        >>> turtle.dot()
        >>> turtle.fd(50); turtle.dot(20, "blue"); turtle.fd(50)
        """
        if not color:
            if isinstance(size, (str, tuple)):
                color = self._colorstr(size)
                size = self._pensize + max(self._pensize, 4)
            else:
                color = self._pencolor
                if not size:
                    size = self._pensize + max(self._pensize, 4)
        else:
            if size is None:
                size = self._pensize + max(self._pensize, 4)
            color = self._colorstr(color)

This is the corresponding type hint in typeshed:

    @overload
    def dot(self, size: int | _Color | None = None) -> None: ...
    @overload
    def dot(self, size: int | None, color: _Color, /) -> None: ...
    @overload
    def dot(self, size: int | None, r: float, g: float, b: float, /) -> None: ...

And this is what the docs state (https://docs.python.org/3/library/turtle.html#turtle.dot):

turtle.dot()
turtle.dot(size)
turtle.dot(color, /)
turtle.dot(size, color, /)
turtle.dot(size, r, g, b, /)

I dont think there is a way to achieve the current desired behaviour without this

[adorilson]

Intentional, however:

cpython/Lib/turtle.py

Lines 3501 to 3503 in 4ac16dd
if isinstance(size, (str, tuple)):
color = self._colorstr(size)
size = self._pensize + max(self._pensize, 4)

So I shall mark this as a feature.

I saw this. The problem seems to be on 3502 line.

After, the color variable will be used in

cpython/Lib/turtle.py

Lines 3520 to 3523 in 4ac16dd

	self.pendown()
	self.pensize(size)
	self.pencolor(color)
	self.forward(0)

I think we just need to erase the 3502 line.

[JanEricNitschke]

If you want to allow all three of these

turtle.dot(3)
turtle.dot("blue")
turtle.dot(size=3)

then i dont think there is a way to NOT have

turtle.dot(size="blue")

[adorilson]

If you want to allow all three of these

turtle.dot(3)
turtle.dot("blue")
turtle.dot(size=3)

then i dont think there is a way to NOT have

turtle.dot(size="blue")

I got your point.

Is it possible to identify if an argument was passed by position or by name?

[StanFromIreland]

Is it possible to identify if an argument was passed by position or by name?

In general, no, such information is not preserved. We could convert it to dot(*args, **kwargs) and we could then distinguish positional vs keyword, but implementing it with all of the required additional handling is quite messy, and not worth the additional complexity in this case IMO.

[jsbueno]

What about having an ad-hoc wrapper which could use *args and **kwargs (and functools.wraps to preserve the original signature), and then error on a non-numeric "size" passed by name?