TFS 1.X+ tfs 1.x doubt getNextPosition

[roriscrave]

My player is in pos: "Position: 360, 734, 7"
And i'm looking for the south: "360, 735, 7"

firt code:

function onUse(player, item, fromPosition, target, toPosition, isHotkey)
    local playerPos = player:getPosition()
    local direction = player:getDirection()
    local newPos = playerPos:getNextPosition(direction)
 
    print("You are in pos: "..playerPos.x..", "..playerPos.y..".")
    print("You are looking pos: "..newPos.x..", "..newPos.y..".")
    return true
end

this first code print incorrect newPos, look it:


and this second script, all prints correct, but why it occours??
i have only changed line 4.

function onUse(player, item, fromPosition, target, toPosition, isHotkey)
    local playerPos = player:getPosition()
    local direction = player:getDirection()
    local newPos = player:getPosition():getNextPosition(direction)
 
    print("You are in pos: "..playerPos.x..", "..playerPos.y..".")
    print("You are looking pos: "..newPos.x..", "..newPos.y..".")
    return true
end

resume:
if i use this form, the script dont work fine:

local direction = player:getDirection()
local playerPos = player:getPosition()
local newPos = playerPos:getNextPosition(direction)

and if i use this form, all works fine

local direction = player:getDirection()
local newPos = player:getPosition():getNextPosition(direction)

but i don't know why it happens, could someone explain to me?

 

[Infernum]

You need to add return self to Position.getNextPosition before the last end in data/lib/core/position.lua.

Edit: Nevermind I completely skimmed this and misunderstood, can you show what your Position.getNextPosition functionlooks like?

 

[roriscrave]

You need to add return self to Position.getNextPosition before the last end in data/lib/core/position.lua.

Edit: Nevermind I completely skimmed this and misunderstood, can you show what your Position.getNextPosition functionlooks like?

here are my current getNextPosition:

function Position:getNextPosition(direction, steps)
    local offset = Position.directionOffset[direction]
    if offset then
        steps = steps or 1
        self.x = self.x + offset.x * steps
        self.y = self.y + offset.y * steps
    end
    return self
end

 

[Infernum]

Ah, I understand now.
You're saving the player's position as a variable and attempting to print the original position value after it's already been changed via Position.getNextPosition.
Tables in Lua are references, if you pass a table to a function and edit it, the original is altered, not a copy of it. So when you save player:getPosition() to playerPos and then use playerPos:getNextPosition(direction), it edits playerPos (see self.x = ... and self.y = ... inside the function) and also returns it. So in the end after you use the next position, you're left with the intended next position being assigned to newPos, but playerPos is the same exact thing because it also got edited.
If you want the original behavior to work as intended, you need to copy the position and edit the copy and return it instead:

function Position:getNextPosition(direction, steps)
    local copy = Position(self.x, self.y, self.z)
    local offset = Position.directionOffset[direction]
    if offset then
        steps = steps or 1
        copy.x = copy.x + offset.x * steps
        copy.y = copy.y + offset.y * steps
    end
    return copy
end

 

[roriscrave]

Ah, I understand now.
You're saving the player's position as a variable and attempting to print the original position value after it's already been changed via Position.getNextPosition.
Tables in Lua are references, if you pass a table to a function and edit it, the original is altered, not a copy of it. So when you save player:getPosition() to playerPos and then use playerPos:getNextPosition(direction), it edits playerPos (see self.x = ... and self.y = ... inside the function) and also returns it. So in the end after you use the next position, you're left with the intended next position being assigned to newPos, but playerPos is the same exact thing because it also got edited.
If you want the original behavior to work as intended, you need to copy the position and edit the copy and return it instead:

function Position:getNextPosition(direction, steps)
    local copy = Position(self.x, self.y, self.z)
    local offset = Position.directionOffset[direction]
    if offset then
        steps = steps or 1
        copy.x = copy.x + offset.x * steps
        copy.y = copy.y + offset.y * steps
    end
    return copy
end

I spent 3 hours trying to understand this shit
I thought I was missing the code, I didn't even think about looking at the function,
THX

Post automatically merged: Jun 6, 2020

Ah, I understand now.
You're saving the player's position as a variable and attempting to print the original position value after it's already been changed via Position.getNextPosition.
Tables in Lua are references, if you pass a table to a function and edit it, the original is altered, not a copy of it. So when you save player:getPosition() to playerPos and then use playerPos:getNextPosition(direction), it edits playerPos (see self.x = ... and self.y = ... inside the function) and also returns it. So in the end after you use the next position, you're left with the intended next position being assigned to newPos, but playerPos is the same exact thing because it also got edited.
If you want the original behavior to work as intended, you need to copy the position and edit the copy and return it instead:

function Position:getNextPosition(direction, steps)
    local copy = Position(self.x, self.y, self.z)
    local offset = Position.directionOffset[direction]
    if offset then
        steps = steps or 1
        copy.x = copy.x + offset.x * steps
        copy.y = copy.y + offset.y * steps
    end
    return copy
end

dont know why, but this new function getNextPosition bugged some things.
when i try to use /attr action,123 for exemple, return this message:

10:59 Item not found.

if i back getNextPosition function to default, the /attr action works fine

 

[Infernum]

I spent 3 hours trying to understand this shit
I thought I was missing the code, I didn't even think about looking at the function,
THX

Post automatically merged: Jun 6, 2020

dont know why, but this new function getNextPosition bugged some things.
when i try to use /attr action,123 for exemple, return this message:

10:59 Item not found.

if i back getNextPosition function to default, the /attr action works fine

It's probably because it's being used as intended in other scripts and wants to alter the original, not return a completely new copy of the next position.
You need to decide what to do next, either wrap that into a new function and just call it something different and call that when you need the copy or change all places where the original is used and make it use the copy instead of the original.

 

[roriscrave]

It's probably because it's being used as intended in other scripts and wants to alter the original, not return a completely new copy of the next position.
You need to decide what to do next, either wrap that into a new function and just call it something different and call that when you need the copy or change all places where the original is used and make it use the copy instead of the original.

i have created a new function getNextPosition with a new name and your code, and ill use it in specific code, it will works fine, thx man!