How can I maintain previous values for property in C#

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3.67/5 (2 votes)

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I want to keep old values (rather I can say original value) and modified value of a variable in same property. the type of property may be int/string/decimal.

for example:
class test{

public int salary{get;set;}
public string month{get;set;}
}

when i use this
test t = new test();
//initializing
t.salary=10;
t.month="apr";
//modifying
t.salary=15;
t.month="mar";

if i do t.salary it will obviously give me last modified value i.e. 15, but i want 10 as well so that it will help me further to show difference.. last value and new value.

is there any way through c# Attributes or any design pattern to keep original value and new value.

I can do this by maintaining two object of test class(original and latest) but there might be lot of properties in a class and only few needs such feature thats why i don't want to maintain two object.

What I have tried:

I thought I can do this using c# attributes but don't know how to do so.

Posted 3-Jan-19 3:01am

ali khanna

Updated 3-Jan-19 6:09am

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[no name] 3-Jan-19 9:18am

Have another property to maintain previous value

3 solutions

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BillWoodruff · Answer 1 · 2019-01-03T06:10:00

First, take a look at these CodeProject articles::

Automated Undo/Redo library based on C# Generics in .NET [^]

Implementing Object Undo and Redo capabilities in .NET [^]

Keep in mind that what's shown here ... what a literal interpretation of your question suggests ... is a stack, a last-in-first-out collection, with a depth of #1. If your goal is to have more than one saved state, consider using the .NET 'Stack data structure.

Using the C# 7 ValueTuple Type [^] , we can make this easy:

C#

private (int Nmber, string Strg) _previousData;

public (int Nmber, string Strg) PreviousData // read-only
{
    get { return _previousData; }
}

private (int Nmber, string Strg) _currentData;

public (int Nmber, string Strg) CurrentData
{
    set
    {
        _previousData = (_currentData.Nmber, _currentData.Strg);
        _currentData = value;
    }
    get { return _currentData; }
}


// test: put in some method or EventHandler
// single-step through the code and observe the values

CurrentData = (100, "x");
CurrentData = (200, "y");

var previous = PreviousData;

int prevNum = previous.Nmber;
string prevStrg = previous.Strg;

F-ES Sitecore · Answer 2 · 2019-01-03T03:36:00

Solution 2

class test{
private int _previousSalary;
private int _salary;

public int salary
{
    get { return _salary; }
    set 
    {
        _previousSalary = _salary;
        _salary = value;
    }
}

Repeat the same idea with month.

Posted 3-Jan-19 3:36am

F-ES Sitecore

Comments

BillWoodruff 3-Jan-19 11:24am

with this, the previous value will never be visible to consumers of the class

F-ES Sitecore 3-Jan-19 12:45pm

If they want it to be public they can add a public property for it. The import thing is that properties don't have to be auto-properties, once the OP understands that they can hopefully come up with the rest of the solution themselves. Give a man a fish and all that.

BillWoodruff 3-Jan-19 13:53pm

"Give a man a fish and all that." Give a man a sloppy drawing of a fish and then ...

Prifti Constantine · Answer 3 · 2019-01-03T03:32:00

C#

public  class test
{
  public int salary{get;set;}
  public string month{get;set;}
}
public class Execute()
{
  //Instantiating test object
  test t  = new test();
  //Creating a list of tests 
  //so we can store the previous values
  List<test> ListOfTests = new List<test>();
//initializing
 t.salary=10;
 t.month="apr";
 ListOfTests.Add(t);
//modifying
 t.salary=15;
 t.month="mar";
 ListOfTests.Add(t);
}
//the previous values now are stored inside the List of tests

How can I maintain previous values for property in C#

3 solutions

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