The 2 columns should be computed:

Segment.Size = Segment.Length * Causeway.Width

Causeway.Size = Sum(Segment.Size[])

First we build the two functions. So back to Visual Studio and add a new class:

public class MultiplyFunction : BcfFunctionBase<decimal> {

[BcfMandatory]

public decimal Value1 { get; set; }

[BcfMandatory]

public decimal Value2 { get; set; }

public override decimal Compute() {

return Value1 * Value2;

}

}

and the second:

public class SumFunction : BcfFunctionBase<decimal?> {

[BcfMandatory]

public decimal[] Values { get; set; }

public override decimal? Compute() {

if (Values == null || Values.Length == 0) return null;

return Values.Sum();

}

}

TIP: Use the BCF codesnippeds.

Now compile the c# project and return to BCF editor.

Switch to "References" tab and click "Add Reference" tool (first tool in upper table). In file dialog select the c# project file (BcfSampleConsole.csproj). Now BCF editor loads the type information of projects output and of all its dependencies. So editor now knows MultiplyFunction and SumFunction. When changing functions you have to recompile the c# project and reload references in BCF editor.

Add a namespace import "BcfSampleConsole" on the same tab. So we can later use function class name without namespace.

Remark: References are loaded into the reflection only context so no code will be executed inside the BCF editor. 

Remark: Placing functions and DataSetSetup into the same project like in this sample is a circular dependency. You cannot generate code without the compiled project and you cannot compile when generated code became invalid. This is not a big deal. In more complex szenarios you should place the functions in another project. In simple szenarios like this you can delete the generated InitSetup method and its call to reenable compilation.

Now back to column [Segment].[Size]. Select or type "MultiplyFunction" into the "Function" field. Switch to "Parameters" tab and add parameter "Value1". In "AccessPath" field enter "Length". Add the second parameter "Value2". Use the access path browser tool by clicking the "Link" button and set "-CausewaySegment.Width" as shown.

Set SumFunction on column [Causeway].[Size] and wireup "Values" parameter with "+CausewaySegment.Size".

Remark: Prefixes "+" and "-" indicate the direction a relation is passed for parameter access.