Output a string representation of the current calling stack, similar to the standard Lua debug.traceback() call, which is not present in WoW.
description = debugstack([thread, ][start[, count1[, count2]]]])
- Thread - a coroutine thread, obtained with coroutine.create(). Use to inspect the current call stack inside a coroutine that has yielded or died.
- Number - the stack depth at which to start the stack trace (default 1 - the function calling debugstack)
- Number - the number of functions to output at the top of the stack (default 12)
- Number - the number of functions to output at the bottom of the stack (default 10)
- String - a multi-line string showing what the current call stack looks like
If there are more than count1+count2 calls in the stack, they are separated by a "..." line.
Assume the following example file, "file.lua":
1: function a() 2: error("Boom!"); 3: end 4: 5: function b() a(); end 6: 7: function c() b(); end 8: 9: function d() c(); end 10: 11: function e() d(); end 12: 13: function f() e(); end 14: 15: function errhandler(msg) 16: print (msg .. "\nCall stack: \n" .. debugstack(2, 3, 2)); 17: end 18: 19: xpcall(f, errhandler);
This would output something along the following:
file.lua:2: Boom! Call stack: file.lua:2: in function a file.lua:5: in function b file.lua:7: in function c ... file.lua:13: in function f file.lua:19
Example 2 Edit
Combining debugstack with a strmatch can enable you to get the current line of a function call.
1: function debugprint(msg) 2: local line = strmatch(debugstack(2),":(%d):"); 3: print("Debug Print on Line "..line.." with message: "..msg); 4: end 5: 6: function doSomething() 7: debugprint("We tried to do something."); 8: end
This would return the following output from print:
Debug Print on Line 7 with message: We tried to do something.
Example 3 Edit
Using debugstack to find out the location of an error in a coroutine.
1: function f() 2: print ("a">0) -- this will cause an error 3: end 4: 5: thread = coroutine.create(f) 6: executed_ok,message = coroutine.resume(thread) 7: 8: if not executed_ok then 9: print("Error: "..message.." in "..debugstack(thread)) 10: end
Note that despite its all-lowercase name, this is not a core Lua function. It is a WoW API.