besnoi / lovelib Goto Github PK

Expected Behavior:

local x = {1,2,3}
table.push_front(x, 4)
for k,v in pairs(x) do
  io.write(tostring(v) .. ", ")
end
-- > 4, 1, 2, 3,

What actually happens:

> 4, 2, 3,

The function being named how it is implies that it would push the value to the front and push other values one index over (sort of like pushing to a stack).

Possible fix:

function table.push_front (tbl, value)
  table.insert(tbl, 1, value)
end

The reason for this being:

local tmp = tbl

Assigns tmp to be a pointer of tbl. If tmp is changed, so will tbl. To achieve the results you are wanting, you need to first clone the contents of tbl.

local tmp = {}
for k,v in pairs(tbl) do
  tmp[k]=v
end

I don't believe there is a need for a recursive cloning function for possible tables since you're only sorting the first layer of elements in the table, so hopefully this would suffice to fix the issue.

The standard table.sort function provided in Lua 5.1 allows for a nil value for the sorting function argument. Having the assert check breaks this as it expects a function only.