SetTableProtected - Revision history

Strix at 09:32, 9 October 2014

2014-10-09T09:32:35Z

← Older revision		Revision as of 09:32, 9 October 2014
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			__NOTOC__
	{{Useful Function}}		{{Useful Function}}
	~~<lowercasetitle></lowercasetitle>~~
	~~__NOTOC__~~
	This function sets a table protected from editing, so if you want to define constants that cannot be changed, this would be a way. I found that function from [http://www.gammon.com.au/forum/bbshowpost.php?bbsubject_id=8028 Internet], by Nick Gammon.		This function sets a table protected from editing, so if you want to define constants that cannot be changed, this would be a way. I found that function from [http://www.gammon.com.au/forum/bbshowpost.php?bbsubject_id=8028 Internet], by Nick Gammon.

Awwu at 20:34, 24 July 2009

2009-07-24T20:34:12Z

← Older revision		Revision as of 20:34, 24 July 2009
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	{{Useful Function}}		{{Useful Function}}
			<lowercasetitle></lowercasetitle>
	__NOTOC__		__NOTOC__
	This function sets a table protected from editing, so if you want to define constants that cannot be changed, this would be a way. I found that function from [http://www.gammon.com.au/forum/bbshowpost.php?bbsubject_id=8028 Internet], by Nick Gammon.		This function sets a table protected from editing, so if you want to define constants that cannot be changed, this would be a way. I found that function from [http://www.gammon.com.au/forum/bbshowpost.php?bbsubject_id=8028 Internet], by Nick Gammon.

Cazomino05: protect_table -> setTableProtected

2009-06-02T08:01:24Z

protect_table -> setTableProtected

← Older revision		Revision as of 08:01, 2 June 2009
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	-- protect my table now		-- protect my table now
	my_constants = ~~protect_table~~ (my_constants) -- it's important to redeclare that variable what you want to protect, since you could still modify the original table.		my_constants = setTableProtected (my_constants) -- it's important to redeclare that variable what you want to protect, since you could still modify the original table.
	my_constants.WIDTH = 11		my_constants.WIDTH = 11
	my_constants.HEIGHT = 11		my_constants.HEIGHT = 11

LordAzamath: setTableProtected - useful function

2009-06-01T17:50:26Z

setTableProtected - useful function

New page

{{Useful Function}}
__NOTOC__
This function sets a table protected from editing, so if you want to define constants that cannot be changed, this would be a way. I found that function from [http://www.gammon.com.au/forum/bbshowpost.php?bbsubject_id=8028 Internet], by Nick Gammon.

==Syntax==
<syntaxhighlight lang="lua">table setTableProtected( table tbl )</syntaxhighlight>

===Required Arguments===
* '''tbl''': The table, which is to be set protected

===Returns===
Returns the table which can't be modified anymore

==Code==
<section name="Server- and/or clientside Script" class="both" show="true">
<syntaxhighlight lang="lua">
function setTableProtected (tbl)
return setmetatable ({},
{
__index = tbl, -- read access gets original table item
__newindex = function (t, n, v)
error ("attempting to change constant " ..
tostring (n) .. " to " .. tostring (v), 2)
end -- __newindex, error protects from editing
})
end
</syntaxhighlight>
</section>

==Example==
<section name="Server- and/or clientside Script" class="both" show="true">
This example shows the above function in work.
<syntaxhighlight lang="lua">my_constants =
{
WIDTH = 22,
HEIGHT = 44,
FOO = "bar",
}

-- protect my table now
my_constants = protect_table (my_constants) -- it's important to redeclare that variable what you want to protect, since you could still modify the original table.
my_constants.WIDTH = 11
my_constants.HEIGHT = 11
-- These will return errors, because _newindex always returns error for that table
-- test it
print ("WIDTH", my_constants.WIDTH) --> WIDTH 22 -- and these remain unchanged
print ("HEIGHT", my_constants.HEIGHT) --> HEIGHT 44

</syntaxhighlight>
</section>

Author: Nick Gammon, commented a bit and found from Internets - Lordy

==See Also==
{{Useful_Functions}}