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 table.remove(tempM) context(#tempM, “, ” , #m) \stopluacode \stopbuffer \starttext getbuffer[test] \stoptext
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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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
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-- ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl -----------------------------------------------------------------
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
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
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participants (4)
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Hans Hagen -
Henri Menke -
Jeong Dal -
Procházka Lukáš Ing.