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Editor to share with you what the role of anonymous methods in the C language, I believe that most people do not know much, so share this article for your reference, I hope you will learn a lot after reading this article. Let's learn about it!

The role of anonymous methods

Do not underestimate the role of anonymous methods. Sometimes you think that their role is limited to the above description, simply because you are not taking a step forward on certain issues. For example, what would you do for objects that only need to be "created on demand" and "thread-safe"? Yes, you can use Double Check:

Private object m_mutex = new object (); private bool m_initialized = false; private BigInstance m_instance = null Public BigInstance Instance {get {if (! this.m_initialized) {lock (this.m_mutex) {if (! this.m_initialized) {this.m_instance = new BigInstance (); this.m_initialized = true } return this.m_instance;}}

Well, you did a great job! So. How about another one of these attributes, three more, and five more? Maybe some friends will start to Copy & Paste a lot, so mistakes are inevitable. Here is a true story. In the past, a classmate was confused in a pile of such code, saying, why did you use this method, or did you initialize the object many times? After checking for a long time, I didn't see the problem. * found that the reason is that the wrong initialized variable was accessed (for example, the articleInitialized was accessed somewhere where the artistInitialized should be accessed). Unfortunately, much of the time has been wasted-and to make matters worse, the mood has become worse.

In fact, Copy & Paste obviously did not follow the DRY principle. Why not encapsulate them in one place? For example:

Public class Lazy {public Lazy (Func func) {this.m_initialized = false; this.m_func = func; this.m_mutex = new object ();} private Func masked function; private bool masked initialized; private object masked mutexes; private T m_value Public T Value {get {if (! this.m_initialized) {lock (this.m_mutex) {if (! this.m_initialized) {this.m_value = this.m_func () This.m_func = null; this.m_initialized = true;} return this.m_value;}}

As a result, the previous code can be simplified to this:

Private Lazy m_lazyInstance = new Lazy (delegate {return new BigInstance ();}); public BigInstance Instance {get {return this.m_lazyInstance.Value;}}

Still too ugly, go to Lambda expression!

Private Lazy m_lazyInstance = new Lazy (() = > new BigInstance ()); public BigInstance Instance {get {return this.m_lazyInstance.Value;}}

Without anonymous methods, many easy-to-use programming models and methods are difficult to develop. For example, we would not have CacheHelper, nor would we have AsyncTaskDispatcher (top and bottom), and it would be difficult to take advantage of the convenience of "delay", let alone excellent frameworks such as Microsoft parallel extensions and CCR. It's fair to say that if you're not good at using delegates, if you don't know how to use anonymous methods properly, you may have written a lot of extra code without knowing it.

One of Lao Zhao's usual jobs is to provide a variety of extended API for the project, so that programmers can develop more happily, get better productivity, and make the code better. Now C# has excellent language features such as anonymous methods, Lambda expressions, expression trees, extension methods, and so on, which makes me feel like a fish in water. Therefore, I can say that I hate such an unenterprising language like Java (Java friends, please learn Scala). When reading a lot of Java open source project code, I often have this feeling: "if it is C #, using anonymous methods, this class can not be written, and that class can be omitted." . That's right, so the role of anonymous methods is to create classes to preserve the context of callback functions, which is a bit of an incredible thing for C # programmers.

As for Lambda expressions and other topics, we'll talk about it next time.

Disadvantages of anonymous methods

The advantage of anonymous methods is that closures are formed automatically, and its disadvantage is that programmers "unconsciously" create closures, which lengthens the life cycle of some objects. For example, in the initial TestRequest method, it appears that url is a parameter and request is a local variable, and some friends may think that they are ready to be recycled after the method exits. However, because of the closure, url and request have been "upgraded" to an object's domain variable, and its lifetime has been extended until the callback function has been executed. As a result, some inexplicable situations may arise if you are not careful.

In fact, these are all traps brought about by "delay". As a good developer, you should not only know the functions and advantages of something, but also know its problems, right?

The above is all the content of the article "what is the function of anonymous methods in C language". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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