Skip to main content

Linq Expression Tree

Linq Expression : Switching between data Structure and code

            /// Linq Expression Tree for (x,y ) => x * y;
            /// Directly build the lambda expression /// 

            Expression lambdaExpression1 = (x, y) => x * y;
            Func lamba1Delegate = lambdaExpression1.Compile();
            int resultLamda1 = lamba1Delegate(100, 100);


     Or you can do the following 

     Expression Func int int int  AddOperation = (x, y) => x + y; 
       int result = AddOperation.Compile()(10, 10);

            ///// Rebuilding and Executing Linq Expression 
            ////  Manually 
            ParameterExpression p1 = Expression.Parameter(typeof(int), "x");
            ParameterExpression p2 = Expression.Parameter(typeof(int), "y");
            BinaryExpression operation = Expression.Multiply(p1, p2);
            Expression> lambdaExpression2 = Expression.Lambda>(operation, new ParameterExpression[] { p1 , p2});

            Func FunctionForLambda2 = lambdaExpression2.Compile();
            int resultLamda2 = FunctionForLambda2(12, 12);


Sample Linq Expression 

Another example to  add x + y + z 

/// x + y + z 

            ParameterExpression varx= Expression.Parameter(typeof(int), "x");
            ParameterExpression vary = Expression.Parameter(typeof(int), "y");
            ParameterExpression varz = Expression.Parameter(typeof(int), "z");

            /// x + y 
            Expression operationAdd = Expression.Add(varx, vary);
            // (x+y) + z 
            Expression operationAdd2 = Expression.Add(operationAdd, varz);
            LambdaExpression expr1 = Expression.Lambda(operationAdd2, varx, vary, varz);
            /// Since we're passing in 3 parameters ..... 
            Func FuncCall2 = (Func)expr1.Compile();
            int result4 = FuncCall2(10, 10, 10);


Popular posts from this blog

Android Programmatically apply style to your view

Applying style to your view (button in this case) dynamically is pretty easy. All you have to do is place the following in your layout folder (res/layout)
Let's call this file : buttonstyle.xml
<?xml version="1.0" encoding="utf-8"?> <selector xmlns:android=""> <item android:state_pressed="true" > <shape> <solid android:color="#449def" /> <stroke android:width="1dp" android:color="#2f6699" /> <corners android:radius="3dp" /> <padding android:left="10dp" android:top="10dp" android:right="10dp" android:bottom="10dp" /> </shape> </item> <item> <shape> <gradient android:startColor="#449def" a…

DataTable does not have AsEnumerable

I have problem locating my AsEnumerable extension method in my DataTabe (System.Data). Thank god for this post by Angel

I was able to find this method once i have added reference to the following assembly.

C:\Program Files\Reference Assemblies\Microsoft\Framework\v3.5\System.Data.DataSetExtensions.dll

Try to do a dummy Build and you should be able to get it.

OpenCover code coverage for .Net Core

I know there are many post out there getting code coverage for .dotnetcore. I'm using opencover to address this needs.

In case, you do no want to use opencover and wanted to stick with vs2015 code coverage, you can try to copy Microsoft.VisualStudio.CodeCoverage.Shim.dll from C:\Program Files (x86)\Microsoft Visual Studio 14.0\Team Tools\Dynamic Code Coverage Tools\coreclr\ and drop it into your project "bin\Debug\netcoreapp1.0" folder.  Please note : you need to be on VS2015 Enterprise to do this. 

To get started, I guess we need to add OpenCover and ReportGenerator for our test projects, as shown in diagram below :-

When nuget packge gets restored, we will have some binaries downloaded to our machine and we going to use this to generate some statistics. I think the biggest issue is to getting those command lines work.

In dotnetcore, we run test project using "dotnet test" (assuming you are in the test project folder - if not please go there)  So we add this …