Item 5: Always Provide ToString()(Effective C#)

系统管理员 2021-11-10 00:22 180阅读 0赞

1 using  System;  
  2  using  System.Collections.Generic;  
  3  using  System.Linq;  
  4  using  System.Text;  
  5   
  6  namespace  EffectiveCSharpItem5  
  7 \{  
  8  public  class  Customer : IFormattable  
  9  \{  
  10  public  string  Name  
  11  \{  
  12  get ;  
  13  set ;  
  14  \}  
  15   
  16  public  decimal  Revenue  
  17  \{  
  18  get ;  
  19  set ;  
  20  \}  
  21   
  22  public  string  ContactPhone  
  23  \{  
  24  get ;  
  25  set ;  
  26  \}  
  27   
  28  public  override  string  ToString()  
  29  \{  
  30  return  Name;  
  31  \}  
  32   
  33  string  System.IFormattable.ToString( string  format, IFormatProvider formatProvider)  
  34  \{  
  35  if  (formatProvider  !=  null )  
  36  \{  
  37  ICustomFormatter fmt  =  formatProvider.GetFormat( this .GetType())  as  ICustomFormatter;  
  38  if  (fmt  !=  null )  
  39  \{  
  40  return  fmt.Format(format,  this , formatProvider);  
  41  \}  
  42  \}  
  43   
  44  switch  (format)  
  45  \{  
  46  case  " r " :  
  47  return  Revenue.ToString();  
  48  case  " p " :  
  49  return  ContactPhone;  
  50  case  " nr " :  
  51  return  string .Format( " \{0,20\}, \{1,10:C\} " , Name, Revenue);  
  52  case  " np " :  
  53  return  string .Format( " \{0,20\}, \{1,15\} " , Name, ContactPhone);  
  54  case  " pr " :  
  55  return  string .Format( " \{0,15\}, \{1,10:C\} " , ContactPhone, Revenue);  
  56  case  " pn " :  
  57  return  string .Format( " \{0,15\}, \{1,20\} " , ContactPhone, Name);  
  58  case  " rn " :  
  59  return  string .Format( " \{0,10:C\}, \{1,20\} " , Revenue, Name);  
  60  case  " rp " :  
  61  return  string .Format( " \{0,10:C\}, \{1,20\} " , Revenue, ContactPhone);  
  62  case  " nrp " :  
  63  return  string .Format( " \{0,20\}, \{1,10:C\}, \{2,15\} " , Name, Revenue, ContactPhone);  
  64  case  " npr " :  
  65  return  string .Format( " \{0,20\}, \{1,15\}, \{2,10:C\} " , Name, ContactPhone, Revenue);  
  66  case  " pnr " :  
  67  return  string .Format( " \{0,15\}, \{1,20\}, \{2,10:C\} " , ContactPhone, Name, Revenue);  
  68  case  " prn " :  
  69  return  string .Format( " \{0,15\}, \{1,10:C\}, \{2,15\} " , ContactPhone, Revenue, Name);  
  70  case  " rpn " :  
  71  return  string .Format( " \{0,10:C\}, \{1,15\}, \{2,20\} " , Revenue, ContactPhone, Name);  
  72  case  " rnp " :  
  73  return  string .Format( " \{0,10:C\}, \{1,20\}, \{2,15\} " , Revenue, Name, ContactPhone);  
  74  case  " n " :  
  75  case  " G " :  
  76  default :  
  77  return  Name;  
  78  \}  
  79  \}  
  80  \}  
  81   
  82  public  class  CustomFormatter : IFormatProvider, ICustomFormatter  
  83  \{  
  84  \#region  IFormatProvider Members   
  85   
  86  public  object  GetFormat(Type formatType)  
  87  \{  
  88  if  (formatType  ==  typeof (ICustomFormatter))  
  89  \{  
  90  return  this ;  
  91  \}  
  92  return  null ;  
  93  \}  
  94   
  95  \#endregion   
  96   
  97  \#region  ICustomFormatter Members   
  98   
  99  public  string  Format( string  format,  object  arg, IFormatProvider formatProvider)  
 100  \{  
 101  Customer c  =  arg  as  Customer;  
 102  if  (c  ==  null )  
 103  \{  
 104  return  arg.ToString();  
 105  \}  
 106   
 107  return  string .Format( " \{0,50\}, \{1,15\}, \{2,10:C\} " , c.Name, c.ContactPhone, c.Revenue);  
 108  \}  
 109   
 110  \#endregion   
 111  \}  
 112   
 113  class  Program  
 114  \{  
 115  static  void  Main( string \[\] args)  
 116  \{  
 117  IFormattable c1  =  new  Customer() \{ Name = " Ray " , ContactPhone = " 12345 " , Revenue = 200000  \};  
 118   
 119  Console.WriteLine( " Customer record: \{0\} " , c1.ToString( " nrp " ,  null ));  
 120  Console.WriteLine( string .Format( new  CustomFormatter(),  " \{0\} " , c1));  
 121  Console.Read();  
 122  \}  
 123  \}  
 124 \}

转载于:https://www.cnblogs.com/zhtf2014/archive/2011/01/11/1933336.html