藍色情懷

Hide Function Pointer Declarations With a typedef
用 typedef 來隱藏極為繁複的函式指標宣告形式
 
Can you tell what the following declaration means?
你可以說出下列宣告是何含意嗎? 

 
Only few programmers can tell that p is an "array of 10 pointers to a function returning void and taking a pointer to another function that returns void and takes no arguments." The cumbersome syntax is nearly indecipherable. However, you can simplify it considerably by using typedef declarations. First, declare a typedef for "pointer to a function returning void and taking no arguments" as follows:
僅有少數的程式設計者可以闡明這個宣告的意義:
亦即 "p 是一個元素大小為10且指向並返回一個無型態的函式的指標陣列;其內的形式參數,是為帶有一個指向其他函式並返回無型態的指標之函式,且此函式並無任何形式參數."
 

 
Next, declare another typedef for "pointer to a function returning void and taking a pfv" based on the typedef we previously declared:
其次,基於我們先前的型態定義的宣告方式, 而對 "指向一個返回無型態的函式且其內帶有 pfv" 來作為宣告另一種形式的型態定義.

Now that we have created the pf_taking_pfv typedef as a synonym for the unwieldy "pointer to a function returning void and taking a pfv", 
declaring an array of 10 such pointers is a breeze:
此刻我們即可以產生 pf_taking_pfv 型別, 將其型態定義成同義異名的宣告式,使其等同於極為繁複的宣告敘述:"指向返回一無型態的函式並帶有 pfv 的形式參數".
於是定義諸如一個大小為10的函式指標陣列且型別是 pf_taking_pfv, 將是輕而易舉的事情: