How to copy variables - ComputerCraft Forums (archive)

ardera #1

ardera's profile picture

463 posts

Location Germany

Posted 29 August 2012 - 12:42 PM

Hey,
Im working on an feature for my OS (see Signature ^^) that adds windows, (resizeable).
And the first thing i worked on was to replace the term.getSize function only for this program,
so i copied the os.run and the shell.run function and in the os.run function I added a code piece, that
copied the _G table
replaced the term.getSize function in the copied _G table

but it seems that the table are synchronized! When I replaced the term.getSize function in the copied _G table, my OS resized too!

Does anyone know a way to replace the function only in this table?
Or how to emulate a smaller terminal for this program?

I have really no idea how to do that…
Please help :)/>/>

KaoS #2

1548 posts

Location That dark shadow under your bed...

Posted 29 August 2012 - 02:33 PM

in order to copy a table without synchronising it with the original use this code


new_table={}
for k,v in pairs(original_table) do
new_table[k]=v
end

ardera #3

ardera's profile picture

463 posts

Location Germany

Posted 29 August 2012 - 08:48 PM

ah *testing*
EDIT: it didn't work.. it seems that you cant create an copy of _G?

Andybish #4

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14 posts

Posted 29 August 2012 - 09:07 PM

I looked on the LUA site, and underscored capitalized variables are locked as internal variables. Maybe this is something to do with it, I don't know.

Kingdaro #5

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1688 posts

Location 'MURICA

Posted 29 August 2012 - 09:43 PM

Try this:


local g = setmetatable( {}, {__index = _G} )

g being your local copy.

ardera #6

ardera's profile picture

463 posts

Location Germany

Posted 29 August 2012 - 09:49 PM

isn't then g a link to _G? *testing*

Didn't work…

God why you can't copy the _G table? Why?

Kingdaro #7

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1688 posts

Location 'MURICA

Posted 29 August 2012 - 09:57 PM

g is it's own table, however when you try to find a property of g it'll go to _G.

this is basically how OO in lua works.

If that doesn't work, there's a deepcopy function you can use.

g = deepcopy(_G)

It's probably the better way of doing this anyway, due to the fact that just indexing won't copy over all of _G's tables.

ardera #8

ardera's profile picture

463 posts

Location Germany

Posted 29 August 2012 - 10:19 PM

Yay it works! Thanks to Kingdaro for the deepcopy function!

KaoS #9

1548 posts

Location That dark shadow under your bed...

Posted 30 August 2012 - 07:36 AM

:)/>/> but that function essentially does the same thing, it just also copies metatables, does anyone know why mine did not work?

ardera #10

ardera's profile picture

463 posts

Location Germany

Posted 30 August 2012 - 07:57 AM

KaoS, on 30 August 2012 - 07:36 AM said:
:)/>/> but that function essentially does the same thing, it just also copies metatables, does anyone know why mine did not work?

Change this


return setmetatable(new_table, getmetatable(object))

to this


return new_table

I don't know why, but then did mine work