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38 lines
981 B
Lua

--[[--
num_args takes in 5.1 byte code and extracts the number of arguments
from its function header.
--]]--
function int(t)
return t:byte(1)+t:byte(2)*0x100+t:byte(3)*0x10000+t:byte(4)*0x1000000
end
function num_args(func)
local dump = string.dump(func)
local offset, cursor = int(dump:sub(13)), offset + 26
--Get the params and var flag (whether there's a ... in the param)
return dump:sub(cursor):byte(), dump:sub(cursor+1):byte()
end
-- Usage:
num_args(function(a,b,c,d, ...) end) -- return 4, 7
-- Python styled string format operator
local gm = debug.getmetatable("")
gm.__mod=function(self, other)
if type(other) ~= "table" then other = {other} end
for i,v in ipairs(other) do other[i] = tostring(v) end
return self:format(unpack(other))
end
print([===[
blah blah %s, (%d %d)
]===]%{"blah", num_args(int)})
--[=[--
table.maxn is deprecated, use # instead.
--]=]--
print(table.maxn{1,2,[4]=4,[8]=8) -- outputs 8 instead of 2
print(5 --[[ blah ]])