如何在c#中做“内联函数”?我想我不明白这个概念。它们像匿名方法吗?比如函数?
注意:答案几乎完全涉及内联函数的能力,即。用被调用者的主体替换函数调用站点的手册或编译器优化。如果你对匿名(又名lambda)函数感兴趣,请参阅@jalf的回答或每个人都在谈论的“lambda”是什么?
如何在c#中做“内联函数”?我想我不明白这个概念。它们像匿名方法吗?比如函数?
注意:答案几乎完全涉及内联函数的能力,即。用被调用者的主体替换函数调用站点的手册或编译器优化。如果你对匿名(又名lambda)函数感兴趣,请参阅@jalf的回答或每个人都在谈论的“lambda”是什么?
当前回答
The statement "its best to leave these things alone and let the compiler do the work.." (Cody Brocious) is complete rubish. I have been programming high performance game code for 20 years, and I have yet to come across a compiler that is 'smart enough' to know which code should be inlined (functions) or not. It would be useful to have a "inline" statement in c#, truth is that the compiler just doesnt have all the information it needs to determine which function should be always inlined or not without the "inline" hint. Sure if the function is small (accessor) then it might be automatically inlined, but what if it is a few lines of code? Nonesense, the compiler has no way of knowing, you cant just leave that up to the compiler for optimized code (beyond algorithims).
其他回答
你是指c++意义上的内联函数吗?其中一个正常函数的内容被自动内联复制到callsite?最终的结果是,在调用函数时实际上不会发生函数调用。
例子:
inline int Add(int left, int right) { return left + right; }
如果是,那么没有,c#中没有与之等价的东西。
或者你是指在另一个函数中声明的函数吗?如果是的话,c#通过匿名方法或lambda表达式来支持。
例子:
static void Example() {
Func<int,int,int> add = (x,y) => x + y;
var result = add(4,6); // 10
}
Lambda表达式是内联函数!我认为,c#没有额外的属性,比如内联或类似的东西!
没错,唯一的区别是它返回一个值。
简化(不使用表达式):
列表> < T。ForEach执行一个操作,它不期望返回结果。
所以Action<T>委托就足够了。说:
List<T>.ForEach(param => Console.WriteLine(param));
就等于说:
List<T>.ForEach(delegate(T param) { Console.WriteLine(param); });
不同之处在于参数类型和委托声明是根据用法推断的,在简单的内联方法上不需要花括号。
而
列表> < T。接受一个函数,期待一个结果。
因此,一个Function<T, bool>将被期望:
List<T>.Where(param => param.Value == SomeExpectedComparison);
也就是:
List<T>.Where(delegate(T param) { return param.Value == SomeExpectedComparison; });
你也可以内联声明这些方法,并将它们赋值给变量IE:
Action myAction = () => Console.WriteLine("I'm doing something Nifty!");
myAction();
or
Function<object, string> myFunction = theObject => theObject.ToString();
string myString = myFunction(someObject);
我希望这能有所帮助。
你把两个不同的概念混在一起了。函数内联是对语义没有影响的编译器优化。不管函数是否内联,它的行为都是一样的。
另一方面,lambda函数纯粹是一个语义概念。对于它们应该如何实现或执行没有要求,只要它们遵循语言规范中规定的行为即可。如果JIT编译器喜欢,它们可以内联,如果不喜欢,则不可以。
c#中没有内联关键字,因为这是一种通常可以留给编译器的优化,尤其是在JIT语言中。JIT编译器可以访问运行时统计信息,这使它能够比编写代码时更有效地决定内联哪些内容。函数将内联,如果编译器决定,没有什么你可以做的任何方式。:)
The statement "its best to leave these things alone and let the compiler do the work.." (Cody Brocious) is complete rubish. I have been programming high performance game code for 20 years, and I have yet to come across a compiler that is 'smart enough' to know which code should be inlined (functions) or not. It would be useful to have a "inline" statement in c#, truth is that the compiler just doesnt have all the information it needs to determine which function should be always inlined or not without the "inline" hint. Sure if the function is small (accessor) then it might be automatically inlined, but what if it is a few lines of code? Nonesense, the compiler has no way of knowing, you cant just leave that up to the compiler for optimized code (beyond algorithims).