[Lua] functions in Lua

The function in lua is a first-class function, which means that the lua function is not the same as that in C/C ++.

Local function print ()
-- Code here
End

-- Actually
Local print = function () -- anonymous function
-- Code here
End

Because the function is a first-class function, you can use a variable to index the function. In this case, the context information of the function also allows you to access external information in the function body. (This is a closure. If you are interested, go to the wiki)

This code is often seen:

Tb = {}
Function tb. print ()
End

In fact, with the above knowledge, we can also know that the Code just now is

Tb. print = function ()
End

In a table object such as tb, there is a print key, and the corresponding value is a function.

And: Call function parameter transfer:

The meaning of tb. print is slightly different from that of tb: print. Calling a function will pass in one more self, which is almost equivalent to calling a member function in OOP.
However, unlike the member function/non-member function in OOP, the non-member function in lua is called rather than static.
The tb object has a print function member. When tb is nil, you cannot call the print member... in OOP, this is not the case. Non-member functions are global.

PS: a previous company asked. the difference between member and non-member functions is actually a bit wrong. lua is a dynamic language, which is very different from C/CPP.