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[unity project practice] entrustment

2022-07-23 19:53:00 【51CTO】

What is a delegate ？

Upgraded version of function pointer , Indirect realization

Data and algorithm are essentially addresses

Call directly ： Call by function name , Get the address of the function directly And start execution

Indirect realization ： Read the address of the function stored by the function pointer And start execution

Java Direct access to the address is not allowed

Action and Func They are all entrusted

Action entrust

Action The return value and parameter list are empty , Only those who meet this condition can be used Action

       
       Action 
       
       action 
       
       = 
       
       new 
       
       Action(
       
       calculator.
       
       Report);
       
       // All you need here is the method name , There is no need to put parentheses after it 
       
       calculator.
       
       Report();
       
       // Call directly 
       
       action.
       
       Invoke();
       
       // Indirect invocation 
       
       action();
       
       // Abbreviated version of indirect call 
      
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Func entrust

Commissioned by the generic Func<>

Write the parameter type and return value type in angle brackets

       
       Func
       
       <
       
       int, 
       
       int, 
       
       int
       
       > 
       
       func1
       
       = 
       
       new 
       
       Func
       
       <
       
       int, 
       
       int, 
       
       int
       
       >(
       
       calculator.
       
       Add);
       
       Func
       
       <
       
       int, 
       
       int, 
       
       int
       
       > 
       
       func2
       
       = 
       
       new 
       
       Func
       
       <
       
       int, 
       
       int, 
       
       int
       
       >(
       
       calculator.
       
       Sub);
       
       int 
       
       x
       
       =
       
       100;
       
       int 
       
       y
       
       =
       
       200;
       
       int 
       
       z
       
       =
       
       0;
       
       z 
       
       = 
       
       func1.
       
       Invoke(
       
       x, 
       
       y);
       
       z 
       
       = 
       
       func1(
       
       x, 
       
       y);
       
       // Abbreviated version of indirect call 
      
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Declaration delegation

Delegation is a kind of , Class is a data type of reference type .

Declaration format ：

Parallel to class level

       
       // Statement ming
       
       public 
       
       delegate 
       
       double 
       
       Calc(
       
       double 
       
       x, 
       
       double 
       
       y);
       
       // Type constraint 
       
       // Instantiation 
       
       Calc 
       
       calc1
       
       = 
       
       new 
       
       Calc(
       
       calculator.
       
       Add);
       
       // When instantiating, fill in the method name in brackets , The method needs to be consistent with that in the declared delegate 
       
       // call 
       
       c
       
       = 
       
       calc1.
       
       Invoke();
       
       c
       
       = 
       
       calc1;
      
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Delegate and encapsulated methods must be type compatible , That is, the return value type is consistent with the parameter list

data model Separate from the presentation layer

use property To write data model

       
       public 
       
       static 
       
       calss 
       
       CounterModel{
       
       private 
       
       static 
       
       int 
       
       mCount 
       
       =
       
       0;
       
       public 
       
       static 
       
       Action
       
       <
       
       int
       
       > 
       
       OnCountChanged;
       
       public 
       
       static 
       
       int 
       
       Count{
       
       get {
       
       return 
       
       mCount;}
       
       set { 
       
       if (
       
       value 
       
       != 
       
       mCount){
       
       mCount 
       
       = 
       
       value;}}
       
  }
       
}
       
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