如何修補或替換Lua中的函數（具有恢復能力）

Question

我認爲我錯過了代碼中的某些東西，要麼是我的「僞代碼」不正確，要麼函數沒有通過Lua中的引用傳遞..
我只想要一個小型庫，它允許我用另一個函數修補/替換一個函數，但能夠將修補後的函數恢復到原始函數。

也許有人已經在過去製作過這樣的圖書館（我找不到它）。

我當前的代碼：

--[[ 
When user wants to patch/replace/detour a variable of type "function" to equal to another variable of type "function", we should always first check user's input, that is the following question - have user supplied valid arguments. 
If invalid argument is caught, then throw an error to the user. 
Now we know that user have supplied valid arguments, next we should check if supplied function (that is to be patched) is already patched function, if it is then throw an error to the user. 
Now we save supplied function (the one to be patched) in a global table (to allow user to restore it later using another function). 
Finally, we assign a function (the one to be patched) to the second function that user have supplied. 


When user wants to restore original function, we should again check user's input first, that is, have user supplied a function and if so - is it really patched. 
Now we know that user have supplied valid argument, so lets restore original function by looking-up in a global table (where we saved original function). 
If by any chance original function is not found, just throw an error to the user. 
We have all information at this point, assign a patched function (from user's input) to the original function. 
Finally, clean-up, remove original function information from our global table (as it is no longer patched). 
--]] 

ftbl = ftbl or {} 

patchf = function(dest, src) 
    assert(type(dest) == "function", "bad argument #1 (function expected, got " .. type(dest) .. ")") 
    assert(type(src) == "function", "bad argument #2 (function expected, got " .. type(src) .. ")") 
    assert(not ftbl[src], "destination is already patched/same source exists") 
    ftbl[src] = dest 
    dest = src 
end 

restoref = function(src) 
    assert(type(src) == "function", "bad argument #1 (function expected, got " .. type(src) .. ")") 
    assert(type(ftbl[src]) == "function", "source is not patched/source does not exists") 
    fsrc = ftbl[src] 
    ftbl[src] = nil 
end 

local my_function = function() 
    print("Hello from my_function :D", 1) 
end 

local another_function = function() 
    print("Hello from another_function D:", 2) 
end 

patchf(another_function, my_function) 

another_function() -- Hello from another_function D: 2 

正如你所看到的，它並沒有打補丁與創建my_function another_function。

Answer 1

任何想法如何也使它在本地功能上工作（如在 當前代碼中所見）？

您不需要用另一個本地函數替換本地函數的庫。只需做一個簡單的分配操作。

例如：

local fu = function() 
    print "fu" 
end 

local fu_new = function() 
    print "new fu" 
end 

fu() 
fu, fu_new = fu_new, fu 
fu() 
fu, fu_new = fu_new, fu 
fu() 

將輸出這樣的：

fu 
new fu 
fu