debugstack
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Returns a string representation of the current calling stack.
description = debugstack([coroutine,] [start[, count1[, count2]]])
Arguments
Parameters
- coroutine
- Thread - The thread with the stack to examine (default - the calling thread)
- start
- number - the stack depth at which to start the stack trace (default 1 - the function calling debugstack, or the top of coroutine's stack)
- count1
- number - the number of functions to output at the top of the stack (default 12)
- count2
- number - the number of functions to output at the bottom of the stack (default 10)
Returns
- description
- 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.
Long lines may become truncated.
The string ends with an extra newline character.
Example
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
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.
This is a WoW API modified version of Lua's debug.traceback() function.
Patch changes
Patch 10.1.0 (2023-05-02): This function will now return no results when called within a __gc finalizer.