Difference between revisions of "LUA Utility Functions"
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Useful functions | Useful functions | ||
+ | |||
+ | == Clone / Deep Copy == | ||
+ | Useful for making a copy of the object. See the OOP example object for it in action. | ||
+ | |||
+ | <syntaxhighlight lang="lua"> | ||
+ | function clone (t) -- deep-copy a table | ||
+ | if type(t) ~= "table" then return t end | ||
+ | local meta = getmetatable(t) | ||
+ | local target = {} | ||
+ | |||
+ | local keys = table.keys(t); | ||
+ | |||
+ | io.write("Keys array is: " .. type(keys) .. "\n"); | ||
+ | io.write("Keys length is: " .. #keys .. "\n"); | ||
+ | |||
+ | for i=1, #keys do | ||
+ | local key = keys[i]; | ||
+ | local value = t[key]; | ||
+ | io.write("Key: " .. key .. "\n"); | ||
+ | |||
+ | if key == "__metatable" then | ||
+ | -- do nothing, metatable is handled separately (how to make lua not complain about empty if's?) | ||
+ | elseif type(value) == "table" then | ||
+ | target[key] = clone(value) | ||
+ | else | ||
+ | target[key] = value | ||
+ | end | ||
+ | end | ||
+ | setmetatable(target, meta) | ||
+ | |||
+ | return target | ||
+ | end | ||
+ | </syntaxhighlight> |
Revision as of 05:30, 21 December 2017
Useful functions
Clone / Deep Copy
Useful for making a copy of the object. See the OOP example object for it in action.
function clone (t) -- deep-copy a table
if type(t) ~= "table" then return t end
local meta = getmetatable(t)
local target = {}
local keys = table.keys(t);
io.write("Keys array is: " .. type(keys) .. "\n");
io.write("Keys length is: " .. #keys .. "\n");
for i=1, #keys do
local key = keys[i];
local value = t[key];
io.write("Key: " .. key .. "\n");
if key == "__metatable" then
-- do nothing, metatable is handled separately (how to make lua not complain about empty if's?)
elseif type(value) == "table" then
target[key] = clone(value)
else
target[key] = value
end
end
setmetatable(target, meta)
return target
end