StackTracePlus

StackTracePlus provides enhanced stack traces for Lua 5.1, Lua 5.2, Lua 5.3, LuaJIT and OpenResty.

StackTracePlus can be used as a replacement for debug.traceback. It gives detailed information about locals, tries to guess function names when they're not available, etc, so, instead of

lua5.1.exe: D:\trunk_git\sources\stacktraceplus\test\test.lua:10: attempt to concatenate a nil value
stack traceback:
    D:\trunk_git\sources\stacktraceplus\test\test.lua:10: in function <D:\trunk_git\sources\stacktraceplus\test\test.lua:7>
    (tail call): ?
    D:\trunk_git\sources\stacktraceplus\test\test.lua:15: in main chunk
    [C]: ?

you'll get

lua5.1.exe: D:\trunk_git\sources\stacktraceplus\test\test.lua:10: attempt to concatenate a nil value
Stack Traceback
===============
(2)  C function 'function: 00A8F418'
(3) Lua function 'g' at file 'D:\trunk_git\sources\stacktraceplus\test\test.lua:10' (best guess)
    Local variables:
     fun = table module
     str = string: "hey"
     tb = table: 027DCBE0  {dummy:1, blah:true, foo:bar}
     (*temporary) = nil
     (*temporary) = string: "text"
     (*temporary) = string: "attempt to concatenate a nil value"
(4) tail call
(5) main chunk of file 'D:\trunk_git\sources\stacktraceplus\test\test.lua' at line 15
(6)  C function 'function: 002CA480'

Usage

StackTracePlus can be used as a replacement for debug.traceback, as an xpcall error handler or even from C code. Note that only the Lua 5.1 interpreter and OpenResty allows the traceback function to be replaced "on the fly". Interpreters for LuaJIT, Lua 5.2 and 5.3 always calls luaL_traceback internally so there is no easy way to override that.

local STP = require "StackTracePlus"

debug.traceback = STP.stacktrace
function test()
    local s = "this is a string"
    local n = 42
    local t = { foo = "bar" }
    local co = coroutine
    local cr = coroutine.create

    error("an error")
end
test()

That script will output (only with Lua 5.1):

lua5.1: example.lua:11: an error
Stack Traceback
===============
(2)  C function 'function: 006B5758'
(3) global C function 'error'
(4) Lua global 'test' at file 'example.lua:11'
        Local variables:
         s = string: "this is a string"
         n = number: 42
         t = table: 006E5220  {foo:bar}
         co = coroutine table
         cr = C function: 003C7080
(5) main chunk of file 'example.lua' at line 14
(6)  C function 'function: 00637B30'

StackTracePlus is aware of the usual Lua libraries, like coroutine, table, string, io, etc and functions like print, pcall, assert, and so on.

You can also make STP aware of your own tables and functions by calling add_known_function and add_known_table.

local STP = require "StackTracePlus"

debug.traceback = STP.stacktrace
local my_table = {
    f = function() end
}
function my_function()
end

function test(data, func)
    local s = "this is a string"

    error("an error")
end

STP.add_known_table(my_table, "A description for my_table")
STP.add_known_function(my_function, "A description for my_function")

test( my_table, my_function )

Will output:

lua5.1: ..\test\example2.lua:13: an error
Stack Traceback
===============
(2)  C function 'function: 0073AAA8'
(3) global C function 'error'
(4) Lua global 'test' at file '..\test\example2.lua:13'
        Local variables:
         data = A description for my_table
         func = Lua function 'A description for my_function' (defined at line 7 of chunk ..\test\example2.lua)
         s = string: "this is a string"
(5) main chunk of file '..\test\example2.lua' at line 19
(6)  C function 'function: 00317B30'

Installation

The easiest way to install is with LuaRocks.

• luarocks install stacktraceplus

If you don't want to use LuaRocks, just copy StackTracePlus.lua to Lua's path.

License

StackTracePlus is available under the MIT license.