Question

This is a segue to my previous question:

Looking for a better way to sort my List<T>

Basically, I have a similar situation where I need to do a .GroupBy() on about 40 different fields.

The original code would have used a giant switch statement, but I’d like to know if there’s a better way to this.

What I’d really like to do is something like:


// not sure what the GroupBy selector function def should be...

Dictionary<PortfolioMapping, Func<Holding, ???>> groupByMappings;


which I can use to group by like:


myPortfolioHoldings.GroupBy(groupByMaping[frmGroupBySelector.SelectedColumn]);


What would be the correct way to go about this?

Answer 1

You should be able to group by object:

Dictionary<PortfolioMapping, Func<Holding, object>> groupByMappings;

This will work as long as your mapping functions return either:

• Instances of built-in types (such as number or strings)
• Objects that implement IEquatable<T>
• Objects that implement Equals and GetHashCode correctly