lua_Debug

lua_Debug

typedef struct lua_Debug {
  int event;
  const char *name;           /* (n) */
  const char *namewhat;       /* (n) */
  const char *what;           /* (S) */
  const char *source;         /* (S) */
  int currentline;            /* (l) */
  int linedefined;            /* (S) */
  int lastlinedefined;        /* (S) */
  unsigned char nups;         /* (u) number of upvalues */
  unsigned char nparams;      /* (u) number of parameters */
  char isvararg;              /* (u) */
  char istailcall;            /* (t) */
  char short_src[LUA_IDSIZE]; /* (S) */
  /* private part */
  other fields
} lua_Debug;

A structure used to carry different pieces of information about a function or an activation record. lua_getstack fills only the private part of this structure, for later use. To fill the other fields of lua_Debug with useful information, call lua_getinfo.

The fields of lua_Debug have the following meaning:

• source: the name of the chunk that created the function. If source starts with a '@', it means that the function was defined in a file where the file name follows the '@'. If source starts with a '=', the remainder of its contents describe the source in a user-dependent manner. Otherwise, the function was defined in a string where source is that string.
• short_src: a "printable" version of source, to be used in error messages.
• linedefined: the line number where the definition of the function starts.
• lastlinedefined: the line number where the definition of the function ends.
• what: the string "Lua" if the function is a Lua function, "C" if it is a C function, "main" if it is the main part of a chunk.
• currentline: the current line where the given function is executing. When no line information is available, currentline is set to -1.
• name: a reasonable name for the given function. Because functions in Lua are first-class values, they do not have a fixed name: some functions can be the value of multiple global variables, while others can be stored only in a table field. The lua_getinfo function checks how the function was called to find a suitable name. If it cannot find a name, then name is set to NULL.
• namewhat: explains the name field. The value of namewhat can be "global", "local", "method", "field", "upvalue", or "" (the empty string), according to how the function was called. (Lua uses the empty string when no other option seems to apply.)
• istailcall: true if this function invocation was called by a tail call. In this case, the caller of this level is not in the stack.
• nups: the number of upvalues of the function.
• nparams: the number of fixed parameters of the function (always 0 for C functions).
• isvararg: true if the function is a vararg function (always true for C functions).