monostate

Singleton mode and monostate mode both force the singularity of objects. Sometimes it seems redundant to force a single object mechanism, but if this mechanism is lightweight, the benefits of conveying intent will be better than the cost of implementing these mechanisms.The most common use of the singleton mode is as follows: Use a private constructor, a static variable, and a static method to control and restrict instantiation. To ensure thread secur

Http://www.phpweblog.net/young40/archive/2007/11/21/2365.html Generally, there is a one-to-many relationship between a class and an object (an instance of a class). But in some cases, we onlyAn instance of a class is required. For example, the diversity of multiple instances will bring some uncontrollable factors, manySecond instantiation, is a kind of resource waste, reduces the efficiency; and if they are factory objects (factoryObject), to create other objects in the system, and so on. At thi

The last time we had a brief look at what a singleton pattern is, we continue to explore today.Last content point this Python design pattern singleton mode (i) Last time we were talking about the GOF design pattern, which means that a class has only one object. What we usually need is to have the instance share an identical configuration, such as a database connection. Alex Martelli's advice is that developers should focus on state and behavior rather than identity, so it's also known as

property, and if it is not found, continues to find the parent class with the same rule. If "__metaclass__" is not found in any of the parent classes, the built-in type is used to create the class object.Of course, for Python3, a new method for declaring a singleton is added:Class Test (Metaclass = Mymeta): Pass　　Three, Monostate modeFor the above singleton pattern, the focus is on generating a single instance, and the programmer usually needs to

The concept of "Singleton" is that there is only one copy of data within the specified range. The "specified range" may be process, AppDomain, thread, or call. Different technologies may be used to create a single instance within a specified range. For example, a common static attribute Instance can provide a very happy range for each AppDomain; a static field modified by ThreadStaticAttribute can provide a range for each thread; and a CallContextStaticAttribute (which must be customized, to pr

Command mode Command mode Active Object Mode Is the application of commandIs the Basic Technology for implementing MultithreadingApplication of active object concurrency mode in Java Http://www.ibm.com/developerworks/cn/java/j-lo-activeobject/index.html Template Method and Policy Mode Why is combination inherited (or policy mode due to template method): the Policy mode has one more intermediate layer than the template method, and the policy mode fully complies with the dip principle, each specif

facade mode is suitable for a wide and visible strategy, while the Medlator mode is suitable for covert and targeted strategies. Facdes is usually the agreed attention point. Mediator is hidden from the user, and its strategy is a fait accompli rather than an agreed thing.The singleton mode uses a private constructor, a static variable, and a static method to control and limit the instantiation. The monostate mode simply turns all variables of the ob