LuaTeX Function Arguments Variables Parameters List ConTeXt Lua \startluacode

LuaTeX Function Arguments Variables Parameters List ConTeXt Lua \startluacode

[Mathieu Dupont]

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Hi List,
I am trying to program with Lua but there are concepts I must not understand, and the documentation is somewhat lacking.
The only useful thing I could use is Hans' manual, thanks to him.
If someone could help me just understanding the concept I must me missing in this simple example I would appreciate it.
So here it is.
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.
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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___________________________________________________________________________________

Re: LuaTeX Function Arguments Variables Parameters List ConTeXt Lua \startluacode

[Philipp Gesang]

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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
> 
> 
> 
> 
> 
>  		 	   		   		 	   		  

> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to the Wiki!
> 
> maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
> archive  : http://foundry.supelec.fr/projects/contextrev/
> wiki     : http://contextgarden.net
> ___________________________________________________________________________________


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___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

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wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: LuaTeX Function Arguments Variables Parameters List ConTeXt Lua \startluacode

[Mathieu Dupont]

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Great, thank you very much Philipp.
I will also read this page you pointed and I should understand better Lua then.
http://wiki.contextgarden.net/table_manipulation

Mathieu
 		 	   		   		 	   		   		 	   		  

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___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________