Hi Mathieu,

On 2012-01-27 19:06, Mathieu Dupont wrote:
>
> Hi List,
> Running the following code, variable "a" should not be modified
> by my function, and stay (1,2), but it does get modified and
> becomes (4,2) like the new variable "b" I am creating.

Tables are references. Using the “local” keyword, you generate a
local variable that still points to the original table. Instead,
you need to (deep) copy the table explicitly.

·································································

\starttext

\startluacode

function myFunc(arg)
	local var = table.copy(arg)
	var[1] = var[1] + 3
	return var
end

local a = {1,2}
local b = myFunc(a)

context.type(table.serialize(a)) context[[\par\blank]]
context.type(table.serialize(b)) context[[\par\blank]]

\stopluacode

\stoptext \endinput

·································································

There’s also a function table.fastcopy(), see
<http://wiki.contextgarden.net/table_manipulation#table.fastcopy.28table_t.2C_.5Bboolean_meta.5D.29>

Hth, Philipp



> What is wrong with my code ?
> Thank you for any hint !
> Mathieu
> 
> \starttext
> 
> \startluacode
> 
> function myFunc(arg)
> 	local var = arg
> 	var[1] = var[1] + 3
> 	return var
> end
> 
> local a = {1,2}
> 
> context("a = \\{")
> context(a[1])
> context(",\\;")
> context(a[2])
> context("\\}\\par")
> context("\\blank")
> 
> local b = myFunc(a)
> 
> context("a = \\{")
> context(a[1])
> context(",\\;")
> context(a[2])
> context("\\}\\par")
> context("\\blank")
> 
> context("b = \\{")
> context(b[1])
> context(",\\;")
> context(b[2])
> context("\\}\\par")
> 
> \stopluacode
> 
> \stoptext
> 
> 
> 
> 
> 
>  		 	   		   		 	   		  

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