aop.md

Code Pollution

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Logging , Exception Handling , Validation , Trace , Security ........

class RiskCalculator{
    ILogger _logger;
    public RiskCalculator(ILogger logger){
        
        this._logger=logger;
    }
    
 public void Calculate(){
     
     this._logger.WriteLogContent("asdffghhj");
 }   
}
interface ILogger{
    void WriteLogContent(string content);
}

class FileLogger:ILogger{
    string filePath;
    public void WriteLogContent(string content){
        
    }
    
}

AOP

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Separate functional requirement code from non -functional requirement code

Separate Cross Cutting Concerns

Add Additional Behavior (advice) to existing code without modifying existing code

AOP frameworks

​ weaving

• Compile time

  • Metadata Driven - intermediate language based

  • An-notations , custom Attributes

  • Aspect-j, PostSharp

  • Add advice -> private / public

  • [Log()]
    @Log
    [Exception]
    public void Calculate(){
         
         
     }   
    

• Runtime

  • spring AOP
  • Proxy Pattern + DI Container
  • Add advice for public interface

interface IRiskCalculator{
     void Calculate();
    
}
class LoggerProxyCalculator:IRiskCalculator{
    IRiskCalculator _actualObject;
     ILogger _logger;
    
   public  LoggerProxyCalculator(IRiskCalculator _calculator,ILogger logger){
        this._actualObject=_calculator;
       this._logger=logger;
    }
     public void Calculate(){
     
     this._logger.WriteLogContent("asdffghhj");
      this._actualObject.Calculate();
     this._logger.WriteLogContent("asdffghhj");
 }  
}
class RiskCalculator : IRiskCalculator{

    
 public void Calculate(){
     

 }   
}

interface ILogger{
    void WriteLogContent(string content);
}

class FileLogger:ILogger{
    string filePath;
    public void WriteLogContent(string content){
        
    }
    
}
IRiskCalculator _obj=DIContainer.GetService<IRiskCalculator>();

TDD

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• Inside-out (unit of code --> functionalities)