Return the environment variables of the object.

Returns three values ​​representing thread hook settings: current hook function, current hook mask, current hook count

Returns a table of information about a function. You can provide the function directly, or you can use a number f to represent the function. The number f represents the function running on the corresponding level of the call stack of the specified thread: level 0 represents the current function (getinfo itself); level 1 represents the function that calls getinfo (unless it is a tail call, which is not counted in the stack); etc. . If f is a number greater than the number of active functions, getinfo returns nil.

This function returns the name and value of the local variable whose index is local at layer f of the stack. This function is not only used to access explicitly defined local variables, but also includes formal parameters, temporary variables, etc.

Push the meta table of the value pointed to by the given index onto the stack. If the index is invalid, or there is no metatable for this value, the function will return 0 and nothing will be pushed onto the stack.

Return to the registry table, which is a predefined table that can be used to save any Lua values ​​that C code wants to save.

This function returns the name and value of the up value of function f. If the function does not have that up value, it returns nil.
Variable names beginning with'(‘ (opening brackets) indicate variables without names (code blocks without debugging information).

Set a function as a hook function. The string mask and the number count determine when the hook will be called. A mask is a string composed of the following characters, each character has its meaning:

• ‘c‘: Whenever Lua calls a function, call the hook;
• ‘r‘: Whenever Lua returns from a function, call the hook;
• ‘l‘: Whenever Lua enters a new line, call the hook.

This function assigns value to the local variable of the level-level function on the stack. If there is no such variable, the function returns nil. If the level is out of range, an error is thrown.

Set the meta table of value to table (it can be nil). Return value.

This function sets value to the up value of function f. If the function does not have that upvalue, it returns nil. Otherwise, it returns the name of the upvalue.

If the message has, and it is not a string or nil, the function returns the message without any processing. Otherwise, it returns the stack traceback information of the call stack. The string optional message is added at the beginning of the stack traceback message. The numeric option level indicates which level of the stack to start the traceback (the default is 1, which is where traceback is called).