Debugging And Testing

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[!] VersionNotice: The below code pertains to an older Lua version, Lua 4. It does not run as is under Lua 5.

Asserts, warnings and debugging messages

See also fast_assert in OptimisationCodingTips.

-- Give warning with, optionally, the name of program and file

--   s: warning string

function warn(s)

  if prog.name then write(_STDERR, prog.name .. ": ") end

  if file then write(_STDERR, file .. ": ") end

  writeLine(_STDERR, s)

end



-- Die with error

--   s: error string

function die(s)

  warn(s)

  error()

end



-- Die with line number

--   s: error string

function dieLine(s)

  die(s .. " at line " .. line)

end



-- Die with error if value is nil

--   v: value

--   s: error string

function affirm(v, s)

  if not v then die(s) end

end



-- Die with error and line number if value is nil

--   v: value

--   s: error string

function affirmLine(v, s)

  if not v then dieLine(s) end

end



-- Print a debugging message

--   s: debugging message

function debug(s)

  if _DEBUG then writeLine(_STDERR, s) end

end

Debugging utilities

-- Extend tostring to work better on tables

-- make it output in {a,b,c...;x1=y1,x2=y2...} format; use nexti

-- only output the LH part if there is a table.n and members 1..n

--   x: object to convert to string

-- returns

--   s: string representation

function tostring(x)

  local s

  if type(x) == "table" then

    s = "{"

    local i, v = next(x)

    while i do

      s = s .. tostring(i) .. "=" .. tostring(v)

      i, v = next(x, i)

      if i then s = s .. "," end

    end

    return s .. "}"

  else return %tostring(x)

  end

end



-- Extend print to work better on tables

--   arg: objects to print

function print(...)

  for i = 1, getn(arg) do arg[i] = tostring(arg[i]) end

  call(%print, arg)

end

Here are Get/DiffGlobalNames which can be used to track down accidental global assignments:

-- GetGlobalNames - returns hash table of current

--     global names

--

function GetGlobalNames()

  local names = {}

  for i,x in globals() do

    names[i] = 1

  end

  return names

end



-- DiffGlobalNames - shows diff of current global names

--     vs previously recorded

--

function DiffGlobalNames(t)

  local gtable = globals()

  local deleted = {}



  local added = {}

  for i,x in t do

    if not gtable[i] then

      tinsert(deleted, i)

    end

  end

  for i,x in gtable do

    if not t[i] then

      tinsert(added, i)

    end

  end

  sort(deleted)

  sort(added)

  print("Changes to global names:")

  print("    Deleted")

  for i = 1, getn(deleted) do

    print("        "..deleted[i])

  end

  print("    Added")

  for i = 1, getn(added) do

    print("        "..added[i])

  end

end