local table becomes global

[AggrorJorn]

In the following topic I have a problem were tables seem to be overwriting each other.

http://www.leadwerks.com/werkspace/topic/7133-script-and-local-usage/

 

Rick found the solution to this problem. Declaring lua tables like this:

Script.myTable = {}
--or
local myTable = {}

 

somehow makes them global and thus they will overwrite each other. Rick found out that you can solve this as follow:

 

Script.myTable = nil

function Script:Start()
self.myTable = {}
end

 

Still, it is odd that the first two methods are making tables global. This might be a bug?

[Admin]

This is working as intended. If you declare a value outside a function, as a member of the script, it will be shared across all instances of the script. If you want a value to be unique for each instance of the script, declare it in the Start() function.

[AggrorJorn]

Okay, thanks for answering.

 

*edit

Incorrect summary

So just to be clear: If I want variables that are local to a script an NOT global

 

Local

local pos
local drawColor

function Script:Start()
pos = Vec2(0,0)
drawColor = Vec3(255,0,0)

end

 

Global

local pos
local drawColor

function Script:Start()

end

[Admin]

Shared across all instances of the script:

Script.mytable = {}

function Script:Start()
end

 

Unique for each instance:

function Script:Start()
  self.mytable = {}
end

 

Global variable:

mytable = {}

function Script:Start()
end

 

Global variable:

function Script:Start()
 mytable = {}
end

 

Local variable:

local mytable = {}

function Script:Start()
end

 

Local variable:

function Script:Start()
 local mytable = {}
end

[Rick]

Why are only tables defined outside a function like Script.mytable = {} shared across instances and normal variables aren't? ie. you can have different values per instance for normal variables defined as Script.myvar = 5, meaning defined like this isn't shared, but tables are shared. Seems odd.

 

[edit]

I tested an exposed variable like Script.health and set it's value differently between 4 different entities, but now that I say this when the game loads you must be making the same named variable behind the scenes for self so that self.health is unique now per instance.

[AggrorJorn]

Thanks for the clear post Josh. This helps me a lot. Perhaps it is a smart idea to document this in the scripts documentation.

 

I do agree with Rick on the consistency though. This has been very confusing and costed me a lot of time trying to figure out what I was doing wrong. Luckily, master Rick was able to see what was going on.

[AggrorJorn]

Lets continue this discussion in the programmers forum section as this is not a bug.

http://www.leadwerks.com/werkspace/topic/7133-script-and-local-usage/