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39 lines
858 B
Lua

--- Functions dealing with metatables and tables merging.
--
-- @module gear.meta
-- @copyright 2022 The DoubleFourteen Code Forge
-- @author Lorenzo Cogotti
local meta = {}
--- Test whether 'obj' is an instance of a given class 'cls'.
function meta.isinstance(obj, cls)
repeat
local m = getmetatable(obj)
if m == cls then return true end
obj = m
until obj == nil
return false
end
--- Merge table 'from' into table 'to'.
--
-- For every field in 'from', copy it to destination
-- table 'to', whenever the same field is nil in that table.
--
-- The same process is applied recursively to sub-tables.
function meta.mergetable(to, from)
for k,v in pairs(from) do
if to[k] == nil then
to[k] = type(v) == 'table' and meta.mergetable({}, v) or v
end
end
return to
end
return meta