Is this Python's edu-sig or Monty Python's philosophers club? ;-) ;-) ;-)
Anyone on this list could probably do the following in less than one minute... Run the following program, showing how left() results in a proper turn left >>> from turtle import * >>> forward(40) >>> left(90) >>> forward(40) Now, close the interpreter and run it again, this time with the following >>> from turtle import * >>> setworldcoordinates(-100, 100, 100, -100) >>> forward(40) >>> left(90) >>> forward(40) See how left() no longer correspond to a left() turn for the turtle? André ===== For those reading this on a device that does not have Python installed, below, I show an ascii-simulated representation of forward(100) right(90) forward(100) when the turtle is oriented facing left initially, starting at the position labeled by O and ending at X (example chosen because it is the easiest for me to draw, regardless of whether a proportional font is used or not for this email) X | | | | | ---------------O In the current implementation, with a particular choice for user-defined coordinates , the same instructions might yield the following ----------------O | | | | | X i.e. a right() instruction would result in a left turn, and vice-versa. On Tue, Jun 19, 2018 at 3:01 PM Kevin Cole < kevin.c...@novawebdevelopment.org> wrote: > On Tue, Jun 19, 2018 at 1:40 PM, Andre Roberge <andre.robe...@gmail.com> > wrote: > >> HI, >> >> There seems to be a lot of misunderstanding about this issue. Hopefully, >> the following can help clear it up. >> >> 0. The turtle module includes functions named left() and right() which >> result in the turtle rotating in the corresponding direction on the screen. >> 1. The turtle implementation includes a function, setworldcoordinates(), >> which allows one to have user-defined coordinates (both for the width and >> height of the world) including a choice as to which in which direction the >> coordinates are increasing. The issue has nothing to do with what choice >> is "best"; any user is free to use whatever they want. >> 2. In the current implementation, if one choses some particular >> orientation for the coordinates, the role of left() and right() are >> inverted and no longer correspond to what the user sees on the screen. >> >> The submitted fix simply ensures that, no matter what one chooses for the >> world coordinates via setworldcoordinates, when right() is called in a >> program, the turtle turns right and not left. >> >> André >> > > Ah. Then I did indeed misunderstand the point. And now I'm of two minds > as to whether or not the fix is a fix. I see it as an option, but I also > see the argument that sprites, avatars, turtles, etc, often are designed > with a "head" and a "tail". So, it's back to the whole "stage left" vs. > "left" argument: Are we talking about the virtual creature's left or the > viewer's left? (Or am I misunderstanding yet again? If I'm not > misunderstanding, I would say "Make it a configuration or startup option, > or attribute of setworldcoordinates, or some such." For me, if I'm giving > you directions to my apartment, and say in e-mail "Turn left" I would > expect you to turn to your left, even if you knew which direction I was > currently facing. I would expect an avatar to turn to its left regardless > of my viewing angle.) > > > -- > *Kevin Cole* > <http://novawebdevelopment.org> > NOVA Web Development Co-Op > http://novawebdevelopment.org/ > Arlington, VA >
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