* Re: about table operation in lua-ConTeXt
2017-02-13 5:50 ` about table operation in lua-ConTeXt Jeong Dal
@ 2017-02-13 8:54 ` Henri Menke
2017-02-13 8:56 ` Hans Hagen
2017-02-13 9:22 ` Procházka Lukáš Ing.
2 siblings, 0 replies; 5+ messages in thread
From: Henri Menke @ 2017-02-13 8:54 UTC (permalink / raw)
To: mailing list for ConTeXt users
On 02/13/2017 06:50 AM, Jeong Dal wrote:
> Dear all,
>
> It may be a slight off topic.
> In the following example, I copied a table “m” to “tempM”, and remove the last row of tempM.
> Then the output is “ 2, 2”
> I checked the contents of tempM and m and found that they are same even though I didn’t touch m.
> I want to remove the last row of tempM while keeping the table m untouched.
> Please tell me how to do it.
>
> Thank you.
> Best regards,
>
> Dalyoung
>
> \startbuffer[test]
> \startluacode
> m = {{0, 2, 4},{2, 3 , 4}, {2, 2, -6}}
> local tempM = {}
>
> tempM = m
Do a deep copy
tempM = table.copy(m)
> table.remove(tempM)
> context(#tempM, “, ” , #m)
> \stopluacode
> \stopbuffer
>
> \starttext
> getbuffer[test]
> \stoptext
>
>
>
> ___________________________________________________________________________________
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>
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^ permalink raw reply [flat|nested] 5+ messages in thread* Re: about table operation in lua-ConTeXt
2017-02-13 5:50 ` about table operation in lua-ConTeXt Jeong Dal
2017-02-13 8:54 ` Henri Menke
@ 2017-02-13 8:56 ` Hans Hagen
2017-02-13 9:22 ` Procházka Lukáš Ing.
2 siblings, 0 replies; 5+ messages in thread
From: Hans Hagen @ 2017-02-13 8:56 UTC (permalink / raw)
To: mailing list for ConTeXt users
On 2/13/2017 6:50 AM, Jeong Dal wrote:
> Dear all,
>
> It may be a slight off topic.
> In the following example, I copied a table “m” to “tempM”, and remove the last row of tempM.
> Then the output is “ 2, 2”
> I checked the contents of tempM and m and found that they are same even though I didn’t touch m.
> I want to remove the last row of tempM while keeping the table m untouched.
> Please tell me how to do it.
\startbuffer[test]
\startluacode
local t1 = {{0, 2, 4},{2, 3 , 4}, {2, 2, -6}}
local t2 = t1 -- t2 points to t1
local t3 = table.copy(t1)
table.remove(t3)
context.tocontext(t1)
context.tocontext(t2)
context.tocontext(t3)
\stopluacode
\stopbuffer
\starttext
\getbuffer[test]
\stoptext
> Thank you.
> Best regards,
>
> Dalyoung
>
> \startbuffer[test]
> \startluacode
> m = {{0, 2, 4},{2, 3 , 4}, {2, 2, -6}}
> local tempM = {}
>
> tempM = m
> table.remove(tempM)
> context(#tempM, “, ” , #m)
> \stopluacode
> \stopbuffer
>
> \starttext
> getbuffer[test]
> \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://context.aanhet.net
> archive : https://bitbucket.org/phg/context-mirror/commits/
> 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!
maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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___________________________________________________________________________________
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: about table operation in lua-ConTeXt
2017-02-13 5:50 ` about table operation in lua-ConTeXt Jeong Dal
2017-02-13 8:54 ` Henri Menke
2017-02-13 8:56 ` Hans Hagen
@ 2017-02-13 9:22 ` Procházka Lukáš Ing.
2 siblings, 0 replies; 5+ messages in thread
From: Procházka Lukáš Ing. @ 2017-02-13 9:22 UTC (permalink / raw)
To: mailing list for ConTeXt users
Hello,
tables in Lua are "shared" - there is one copy until you "deep copy" one to another.
Se comments bellow -
On Mon, 13 Feb 2017 06:50:38 +0100, Jeong Dal <haksan@me.com> wrote:
> Dear all,
>
> It may be a slight off topic.
> In the following example, I copied a table “m” to “tempM”, and remove the last row of tempM.
> Then the output is “ 2, 2”
> I checked the contents of tempM and m and found that they are same even though I didn’t touch m.
> I want to remove the last row of tempM while keeping the table m untouched.
> Please tell me how to do it.
>
> Thank you.
> Best regards,
>
> Dalyoung
>
> \startbuffer[test]
> \startluacode
> m = {{0, 2, 4},{2, 3 , 4}, {2, 2, -6}}
> local tempM = {} -- OK, 'tempM' and 'm' are different tables - try 'print(tempM, m)' - you'll get two addresses
>
> tempM = m -- Now, 'tempM' and 'm' will point to the same table - "the 'm' table"
-- The original 'tempM' table will be forgotten and removed during next garbage collection as there is no other reference to it
-- ('tempM' starts pointing to 'm', too)
> table.remove(tempM) -- Will remove from one
> context(#tempM, “, ” , #m) -- Obviously - both table point to the same object, try again 'print(tempM, m)'
> \stopluacode
> \stopbuffer
>
> \starttext
> getbuffer[test]
> \stoptext
Best regards,
Lukas
--
Ing. Lukáš Procházka | mailto:LPr@pontex.cz
Pontex s. r. o. | mailto:pontex@pontex.cz | http://www.pontex.cz | IDDS:nrpt3sn
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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://context.aanhet.net
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : http://contextgarden.net
___________________________________________________________________________________
^ permalink raw reply [flat|nested] 5+ messages in thread