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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.

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These routines provide assertions, warnings, errors, and other debugging facilities one's used to having in other languages. See UnitTesting for discussion about unit testing facilities.

Asserts, warnings and debugging messages

Some of these functions assume the existence of a global line that gives the current line number of the file being processed, if that makes any sense.

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

Also useful for general interactive use: extensions of tostring and hence print to show tables better.

-- 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

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Last edited January 25, 2019 6:39 pm GMT (diff)