Lazy Loading in C #

What is deferred loading?

Lazy loading is the name of the delayed load, which is loaded when it is actually used .

Usually when creating a large object, some properties we can use to create (set the value of the property), which can effectively improve the performance of the system.

Example:

/defines a hero type Public classhero{ Public stringname{Get;Set;}  Public stringfullname{Get;Set;}  PublicSkill Objskill;  PublicHero (stringname) {Name=name; FullName="Super"+name; Objskill=NewSkill (name); }}//define a skill type Public classskill{ Public stringname{Get;Set;}  Public intpower{Get;Set;}  PublicSkill (stringname) {Name=name; Power=name.    Length; }} Public classprogram{ Public Static voidMain (string[] args) {Hero Hero=NewHero ("qi da sheng"); //at this point I just want to get hero's FullName, but also call skill's constructor, load the skill properties,//initializing skill requires a certain amount of space in memory, resulting in unnecessary wasted spaceConsole.WriteLine (Hero.                FullName); //think: What if the implementation actually creates the skill object when calling Skill.name?     }}

Improve A

Improvement One://defines a hero type Public classhero{ Public stringname{Get;Set;}  Public stringfullname{Get;Set;} //Public Skill Objskill;    PrivateSkill _skill;  PublicSkill Objskill {Get{return_skill?? (New_skill (Name));} }         PublicHero (stringname) {Name=name; FullName="Super"+name; //objskill=new Skill (name);    }}//define a skill type Public classskill{ Public stringname{Get;Set;}  Public intpower{Get;Set;}  PublicSkill (stringname) {Name=name; Power=name.    Length; }} Public classprogram{ Public Static voidMain (string[] args) {Hero Hero=NewHero ("qi da sheng"); //when you get hero FullName, you do not create an instance of skillConsole.WriteLine (Hero.        FullName); //do you really use Skill.name to create an instance of skill, which results in lazy loading? Console.WriteLine (Hero.                Objskill.power); //Think 2: Is there any other better way?     }}

Improved two

usingSystem;usingSystem.Collections.Generic;usingSystem.Linq;usingSystem.Text;usingSystem.Threading.Tasks;namespacedemo_lazy{//defines a hero type     Public classHero { Public stringName {Get;Set; }  Public stringFullName {Get;Set; } Private ReadOnlyLazy<skill>skill;  PublicSkill Objskill {Get{returnskill. Value; }        }         PublicHero (stringname) {Name=name; FullName="Super"+name; Skill=NewLazy<skill> (() =NewSkill (Name)); }    }    //define a skill type     Public classSkill { Public stringName {Get;Set; }  Public intPower {Get;Set; }  PublicSkill (stringname) {Name=name; Power=name.        Length; }    }     Public classProgram { Public Static voidMain (string[] args) {Hero Hero=NewHero ("qi da sheng"); //when you get hero FullName, you do not create an instance of skillConsole.WriteLine (Hero.            FullName); //skill instances are created when the skill.name is actually used, resulting in a lazy loading effectConsole.WriteLine (Hero.objSkill.Power);        Console.read (); }    }}

Advantages of Lazy<t>

So why introduce lazy<t> if we can already implement it using the property caching method?

At least lazy<t> has the following advantages:

1. It has lazythreadsafetymode, but we don't normally use it unless it's a critical case (181 words omitted here)
2. It makes the definition row of a property simpler
3. Semantically, it's more explicit and more readable.
4. It allows NULL to be a valid value

Lazy Loading in C #